has anyone experience this? how do you get out of it?
Breaking up with a deeply troubled person can be an act of self help and I believe should be looked at as such. It sounds like you may have been in a situation that was unhealthy for you and perhaps even toxic and therefore you needed to take care of yourself by removing yourself from the turmoil.
I was years ago in a relationship with an undiagnosed bipolar person who was physically violent and it took me a couple years to get out of it with the help of a support group and therapy.
Guilt is a useless emotion and is especially not called for in your situation. You need to feel good about yourself for taking steps to remove yourself from a relationship that wasnt working for you. And life will call upon you to do the same thing many times over, removing yourself from both small and large situations that arent right for you for any number of reasons.