I agree with all of the above completely. Being Bipolar and working in the field as well, I often see people try to blame their bad behavior or character defects on their mental illness. While it may or may not be a contributing factor, I can't justify in my mind that it's the entire problem. There's a lot going on there.

The truth is, it doesn't really matter if its part of the illness or not. What matters at this point is what you are willing to do about it. You can't unlearn what you've already learned. If you feel as though your feelings are strong enough that they can survive this, then forgiveness is in order. If you don't feel that they are, forgiveness is still in order, for your own good, but getting back with her may not be in order. I've been in the same position and chose to forgive, but later had to move on. Its an aweful place to be in and you have my empathy.

I hope things work out for you.