@Lsuslu,
To be honest, I am not sure that she is truly separated, rather in her mind she is.
It's going to take some time for her to break away from this guy as she seems to suffer from low self esteem in my opinion and regardless of you being there for her, she's not ready to face and embrace knowing herself and wanting more out of life of what she deserves.
Nasty messages are, well nasty.
I agree that you need to distance yourself and find someone that is ready for a relationship.
No point either, having some guy come and use you as a punching bag for sleeping with his wife.
Point I am trying to make is "words" can be exactly that. In his mind he is probably still very much married. In hers, separated "but" still married.