I realize how horrible this sounds, but I’m so enamored with my long term boyfriend’s friend…Starting to realize I always have been. My relationship has always been rocky (4 years of ups and downs) and I’ve had doubts since the beginning.
His friend and I hit it off immediately, and he’s honestly my favorite person. I genuinely enjoy his presence more than anyone I know. He’s apparently pretty average looking, but I’ve always been WILDLY attracted to him. He gives the best hugs in the entire world, and I feel like I just GET him. My boyfriend and I have opposite personalities, which I originally thought didn’t matter when I was 19 and naive, but after years of bonding with his friend who has the exact same positive, happy-go-lucky, non-confrontational vibes as me, I’m so hooked. My boyfriend has always been such a pessimist, which turned me off from the beginning, but I never thought until recently that I could find someone who loves me as much as he does, so I’ve put up with his downer personality for years…I realize now that sounds horrible.
I sound like a battered housewife. I’ve wanted to break things off with my boyfriend for a while now but I fear I’ll never see his friend again. I owe it to my boyfriend to leave, but I’m terrified of hurting him as well. He loves me so much, despite our differences. He has depression and I’m honestly worried he’ll hurt himself. I think that’s another reason I haven’t split with him; he tried to kill himself a couple years ago and I’m terrified of putting him in that position. We live together and have two dogs; frankly I get anxiety and nausea just thinking about uprooting their lives with a breakup, so imagining hurting my boyfriend has had me writhing on the floor with stomach pains caused by anxiety. I feel trapped. If anyone has any advice or just ANYTHING to give me some peace of mind, please share. I’d appreciate it SO MUCH.
LemonVibe 
Repeat this to yourself: I am not responsible for another person’s mental illness. I am responsible for me alone.
First break up with him and do not see anyone. You need time to heal, and not desperately jump into someone else’s arms after years of dealing with someone with a mental illness.
Make sure to already have a safe place to go and to remove any pets or children just in case. If you feel he will self harm call 911.
After a few months of healing then you can see if you can pursue a relationship with his friend. There is no such thing as the one. There are over 4 billion people on this earth. Can you comprehend what that means statistically the odds are for you to find a working relationship? It’s mind blowing. Yes, you may have chemistry with the best friends and right now you are desperate for a working relationship, but you can’t have a actual working relationship until YOU heal and YOU make yourself happy. No other person is going to be able to do that for you, because going back to the first thing I said: they are not responsible for another persons’s happiness. Only you are.
That means nothing will change until you decide you’ve had enough and change it.