I Am One But It's A Tough Job Being One

I am a mistress or "the other woman" in my boyfriend's life. It's a rather common but yet different situation. I am also married. This is my second marriage. My first was abusive. I ended up cheating on him to find someone to help me get out. I met my current husband, and left my first and we married. Things were great for awhile, then after I let him reconnect with an old high school sweetheart-clear across the country, via internet, I read their emails and found out that my husband told her that she was the best thing that ever happened to him and blah blah. Other ward, he was just reminiscing, but being a jealous person I am, I got my feelings hurt. I wasn't looking into finding another man, but it happened. The man that I am currently in love with is unhappily married. She is always yelling at him, putting him down (I heard her before-he had recorded her) and she is an alcoholic. She hates him. They don't sleep in same bed or have sex (I don't either with my husband). When they married, she moved into his house, which was in his family. His issue is, he's afraid of losing that house. She can't move out cause the economy, and he won't kick her in the street. But he wishes she'd just leave.
It's frustrating on me tho. I want to start my future with this man, and it's so hard waiting. I hate being the "mistress". I want to make him happy. I want to cook for this man and take care of him. He and I have so much in common. We are both musicians and play same instruments and love the same things. It's like we were meant to be.
But I know she isn't gonna leave. I am a wife, and I haven't been able to leave the home I live in either due to I am not working. My husband knows about my man, and is cool about it. We are more friends and room mates now. We have a child together also. My husband has been trying to help us figure out a way to get her to move out and for him not to lose his home. That is what he is afraid of. He is very supportive and I have been grateful.
I love this other man so much. The thing is I am bi polar and depressive and tend to get so upset cause things aren't speeding up, I pick arguments with him. I don't want to turn out like her.
He doesn't make love to me all the time either. It's not another woman and he's not sleeping with his wife. It's just he's works all week-with one day off and he's always tired. I am younger than him...I am always wanting him to make love and he acts like it is a job or something. IDK. Lots of stress causes it problem in that field...so that is another thing to trigger me off, lol!
I don't want to leave him. everytime I say I am I look into his eyes and I go ga-ga. So I am pretty much stuck. There are other men that want to date me-more active ones too, but damn it, I can't. I love this one man and him only.