My boyfriend and I were discussing various sexual things we would or wouldn’t try last night when he told me that he loved doing one specific thing and had done it a lot in the past. The act is something I’ve been too insecure to do up to this point, and it would take a lot of reassurance for me to be able to do it in the future. I don’t mind that my boyfriend has a past, as I have one myself. He just slipped up by telling me the details about it, and though I realize it was just a mistake on his part, I cannot stop picturing him doing this with all of his ex-girlfriends (who are all hotter, skinnier, more athletic, bigger boobed, and apparently more confident than I am). I need some advice for how to move past this burning image in my head and stop dry-heaving over it. Right now I feel ashamed and just not good enough for him, and I feel like I can’t even look at him right now because I’m too disturbed and insecure about it.
LemonVibe 
[Okay, but in all seriousness, I think we all get a little (sometimes a lot) insecure when we’re with someone we really care about, because we have a lot to lose if it doesn’t work out. So, I think it’s normal that you’re feeling like this. Now, you just have to figure out a way to accept that he’s been with other women in the past, but these are women in his past.
As for how to get over these feelings… sorry, I don’t have any tangible suggestions other than to just give yourself time to wean these images out of your head?
[Obviously we all have things that we will and won’t do in the bedroom. But when you first mention this thing, you seem a little insecure about it, yet not completely disgusted. Then you go on to say how horrifying it is to you, and how it makes you sick. I worry you might be a little naive sexually (which is fine, by the way!)
This could be because you’re insecure, which is totally understandable. I think if you were a little more confident, it wouldn’t be such a big deal. I’m not saying that with more confidence comes more sexual openness, but I think you’re feeling so off about the thing your bf used to do, because you’re comparing yourself to the other girls, and the fact that they could do this thing that you don’t want to do, just adds one more thing to the list of reasons why they’re better than you.
Your boyfriend chose to be with you. Be confident in the fact that for all the great qualities you list about his exes, he didn’t end up with them. He chose you.
If you really are horrified at the thought of trying this new thing in bed, then just have a discussion with him. Tell him you’re sorry if it’s disappointing to him, but you just don’t feel comfortable doing it. He’ll probably understand. But, if it happens to be a deal-breaker for him, then you can move on and can start looking for someone with whom you’re more sexually compatible.
If it’s not so much the act that horrifies you, but the thought of your boyfriend doing it with other people, then having a talk with him about your insecurities is the way to go. He may be willing to just not do it all together. Or, if you’re interested, maybe the two of you can try out a lighter version, or maybe you can try it until you get really uncomfortable, then stop. Just because you’re uncomfortable about something at first doesn’t mean you can’t warm up to it. (Not every teenage girl is totally thrilled about putting a penis in her mouth the first time, but it grows on you, you know?)
Basically, you need to talk to him about this. Clearly you’re insecurities about yourself are getting in the way of you being comfortable in the bedroom. And if you can’t talk about the most intimate things, you probably shouldn’t be doing them.
[OK I know I’m not the only one dying of curiosity about what this thing is, right? Haha!!
OK, in all seriousness. This seems a time for applying the mentality of “accept that which you cannot change”. You can’t change his past, or his other relationships, or the fact that he has (gasp!) had sex with other people.
Honestly what I think is holding you back is that you know he wants to do this thing, and since these “other girls” have done this thing with him it makes you feel, I don’t know… less of a woman in a way. Hence the insecurities.
Well stop it. Everyone has their own personal boundaries in the bedroom. If your guy is worth having, he’d understand that and try to reassure you that you are perfectly compatible without this thing. Perhaps instead of giving him hope that you might try it, by “easing into it” as you say – just tell him it’s off the table. Relieve the pressure off yourself. There’s nothing that says you can’t change your mind at a future date – but for now, if you just tell him in no uncertain terms it’s not happening then you can just have a breather of not having to worry about the sex part of the problem.
As for the other problem, the insecurities… I echo everyone that said he picked YOU. There is absolutely no sense in driving yourself crazy with these visions. You clearly already have a negative image of yourself since you compared them physically in your post. You could benefit from saying affirmations each day until you actually believe that you are special and wonderful, and your boyfriend is with you because he cares about you.
And on the total flip side of everything I said above, I think sometimes the only way to get away from insecurities that are so utterly overwhelming is to just give into the fear and replace old images with new.
[Babe, didn’t I tell you to keep my sheep, uh, “thing” between us?!?
[It’s difficult to have anything to recommend when it comes to helping you get beyond the girlfriends from your guys past.
I’d just say keep reminding yourself that they are precisely that “his past” and you are his present. These women are no longer in his life…but you are; so obviously you have something that they did not.
He wants to be with you. Yes, it may not have been the best move for him to go into details about his past experiences but some guys are very literal and if you ask a question they are going to give you the answer (we think you’ll commend us for our honesty). For that, it may just take time but you’ll get those thoughts/images out of your head.
[Here’s my take as a girl who likes to tell herself that she’s gotten over her body image issues—whether that’s true or not is debatable. This is another case where I think, despite what everyone is telling you (which is great advice, by the way, to talk to your SO, to remember that he chose to be with you, that he likes being intimate with you), you’re going to have to fake it till you make it. If you lack confidence in your own body—and it’s okay to not be confident in your own body, everyone is—then you have to pretend you love it until you actually do. Start acting like you are the hottest woman that’s ever walked the planet, like you know how badly your SO wants you, like you know he is completely mesmerized by you, and sooner or later you’ll start being more comfortable in your own skin. Try as hard as you can to simply shut off that self-critical part of your brain, literally tell it to shut up if you have to. It’s hard, and this doesn’t work for everyone, but it worked for me.
As to the sex act itself, I’m a fan of the Dan Savage GGG model (Good, Giving, Game), but if it’s an act that you really have an objection to because you are morally opposed to it or find it disgusting, then have a conversation with your SO about it, and see if there’s a way to meet half-way, or come to some sort of compromise on it.
[Not trying to be mean or anything, but what kind of response were you expecting? You wanted to know what honestly turns him on, right? The good news is he wants to do that with you . I say do it ands then the image won’t be of others but you.