I don't think its your place to get her professional help. Thats a very personal thing and only she or her family members can advise her to do that but not you. If my ex boyfriend, fiance, or even current boyfriend tried to get me psychiatric help after something like that and I was as crazy as she sounds, I would raise world war 3. Not a good idea at all. Do you think somehow she will be like, "Oh okay you're right, I do need psychiatric help, thank you so much!" Hell no. She will go down kicking and screaming and bring you right down with her.
And of course it's a control/power thing by her saying she can't forgive you - that's a perfect way to turn the situation around to make her seem like the victim. Can you imagine if you actually got the police involved? You'd be taken away in handcuffs.