I’m his Mistress and I’m married, but he’s finally divorced and starting a new job.
I know I shouldn’t expect anything different but we’ve been together for 3 years and he’s leaving to start a new job. On the one hand we’ll have more time together in the evenings because he’ll have his own place, but on the other hand he’ll be surrounded by new colleagues including women that will be interested in him since he’s attractive, successful and now technically single. I know a lot of this is because of my insecurity, but we love each other and I know we will try to make it work. I guess my question is, how do I make sure he doesn’t cheat on me? I know people say once a cheater always a cheater, but still. I asked him to promise that if he meets someone else or wants to pursue something, that he tell me about it before he does it. He tells me that I always plan for the worst case scenario but it kind of feels like it is. It’s a great opportunity for him but he’s leaving me on my own in the process and I’m not sure how to handle not seeing him every day.
Like I said, I’m married and I know people may judge that because it’s hypocritical of me to be upset with him cheating when in fact I’ve been having an affair all this time. I guess I just don’t know what to do to save our relationship but I also don’t want to wait around till it crashes and burns. I feel helpless.
LemonVibe 
whoa now. One problem at a time.
First, it’s time for a talk with your husband about open relationships and polyamourus counseling. Neither of these relationships may be able to be saved, but at least try. You may not be monogamous. You might be using this relationship as escapism. Counseling will help.
Next, you can’t ask anything of the man who was cheating on you, because he owes you nothing. Read that back to yourself. He owes you nothing. It was a affair and not a polyamourus relationship, so not even a boyfriend level.
I don’t think you are a bad person, but focus on your issues instead of running away from them. I’m sure you may love this man and that’s ok in the right circumstances. In the wrong one you will end up hurting just like now. Best wishes to you.
and what about your poor husband in this situation? Why are you staying with your husband? If you also get divorced you will be free to be your Lovers official partner, but do you think he wants that with you, or are you only suitable for a secret affair? If he does find a new girlfriend will you expect him to cheat on her to be with you? I think you are a very selfish person, your thoughts seem to be all about what you want and you have shown little regard to anyone elses feelings. Maybe you should concentrate on genuinely caring for others and then they will show some care for you. Good luck