I just want to say that what happening in the past really doesn't have anything to do with you

If her past makes you that nauseous and makes you feel that bad and you're willing to leave her after being with her for 7 years just because you can't handle her past then maybe that's the best option

Honestly I am surprised she hasn't left you yet
If I was with someone who kept shaming me over my promiscuous past (especially if the reason was peer pressure) I would leave them