I had an experience like this with a woman that I went on a date with about 2 years ago. I met up with this woman, who I had only communicated with over the phone, at a local bar/restaurant and we were having a good time. Anyway, at some point during the conversation she just randomly blurted out how she had been sexually abused growing up. I immediately found it off putting but I overlooked it because she was very attractive and despite my better judgement I went out again with her after that.
As
@TheProspect and
@oldmanofthesea mentioned, the fact that a woman like this is mentioning this to you, a near total stranger, is extremely inappropriate and suggests there are many other issues that she has going on behind the curtains.
As
@soulforge mentioned, women like this have issues that only they themselves can fix and it is in your best interest to move on. Beta white knight game would be trying to go in there and "save" her from herself but you'd just be setting yourself up for a severe degree of stress down the road all for the sake of some validation and sex. However, I also believe that using this woman as a source of sex is simply not something you should encourage. Girls like this are regularly pumped and dumped and by doing this you just continue to encourage this endless cycle and broadening her mental health issues, which is not a very nice thing to do.