I have been seeing a woman for about 3 years. It started out sweet. It was amazing. It lasted about a year. She was divorcing. And soon all those good qualities seemed to fade.
She became very clingy. She was very emotional. If I didn't call by a certain time, she would get angry.
I suggested counseling. It took a lot, but she finally went. She attended counseling for a year. I still didn't see any changes. She still acted abnormal. I told her I would go to counseling with her. Within 3 sessions her therapist suggested bipolar. I feel that while she was attending counseling alone she wasn't as open about sharing her life.

The counselor suggested some separation. And a psychological evaluation for her.
I told her I would help her any way I could. As the months wore on she became worse. She would throw things and get violent. Her grades in college suffered. Her sleep patterns were very odd. She would cry a lot.
It got to the point that anyone I talked to was a "girl I was cheating with". She lived with me for over a year at this point. I told her she had to leave.
She told my mom she was homeless, and my mother took her in.
She stayed there for about a month. Then she moved in right behind me.

Her evaluation said she was bipolar according to her. She has been taking depakote, melatonin, and Paxil.
We started to talk again. And even some light dating. She kept pressing the issue of marriage. She even proposed. I declined.
We still dated, but nothing serious.

She asked me a few days ago if we could work on a serious relationship. I told her yes.
Two days ago I called her and a guy answered her phone. This is her boyfriend now. I was in shock. I still am.

Is this a direct result of bipolar? Or is it typical for someone to switch that quick?

The new guy is nothing like her. She is a family oriented woman and comes from middle class. He is a felon and has shared his opinion about how she needs to be protected. She tells him I'm violent?

I'm sorry this is so long.
Should I wait for her? Or did she do this with a sound mind, and needs no excuse?

Thanks