Hello Hugh Mungus: I see this is your first post here on PC. Welcome to Psych Central.

I want to start out by saying I've been married for almost 40 years! (My wife's accomplishment, not mine.) And I'll tell you it takes an ocean liner's worth of caring, forgiveness, compassion, & just plain stubbornness to keep a romantic relationship going for that long.

From my perspective what's in the past is in the past. You simply have to let it go. You weren't there when your gf did what she did nor were you a part of it. It simply no longer exists. To some extent it's really none of your business really. What's relevant is who this young woman is today & who will she be in the future. And, of course, there are no guarantees.

It does sound as though your gf may have some mental health issues. And so perhaps the question is what is she doing to address her issues & ensure she won't slip back into old habits as time passes. If she's not doing anything, & is not willing to do anything, that is a bad sign to my way of thinking. I would think what might be appropriate would be for her to be receiving some sort of mental health therapy herself &, at some point, for the two of you to engage in some couples counseling. Plus, considering your own level of uncertainty regarding your relationship with this woman, perhaps some mental health therapy services for yourself might be a good idea to help you sort your feelings for her as well as your fears.

You asked how you "squash" your inner conflict & accept who your gf was. My personal opinion is you cannot. There simply is no way to squash feelings. If you cannot put them to rest on your own (& clearly you cannot) the only realistic alternative I know of is to talk them through at-length & in-depth over a period of time with the help of a skilled mental health professional. Perhaps in the end the two of you will decide you were meant to be together. Perhaps not. But at least you will have given it your best shot, so to speak, & gone on with your relationship with your eyes open. That's about all any of us can do. The future is never guaranteed.

Here's a link to an article, from Psych Central's archives, that I think bears some relevance to your situation. The details are different because the article deals with second marriages. But I think the insight the author offers is apropos:

Don't Ask Your Ex Partner to Erase the Past

My best wishes to you both. I hope you find PC to be of benefit.