Does her past indicate she isn't right for me

I’ve been seeing this girl, and our personalities seem to click so well. She is so thoughtful and kind. I really care about her. However, against my better judgement, after the subject sort of came up, I found out she has slept with 20 guys before me. At first, I didn’t care, but now the more I think about it, the more it scares and bothers me. She is bi-sexual, so that is really probably like 40 partners over about 10 years. I’ve been much pickier about who I sleep with, and I’ve been married, which probably hurts her more than if I had slept with 400 girls, but she’s only the 5th woman I’ve slept with. I guess deep down I’m old fashioned and I’m very picky about who I choose to have sex with, and it bothers me that she obviously isn’t. I keep thinking, maybe the only reason she’s in love with me is because I’m the only bleeding heart idiot who didn’t just want to plow through her. She says she used them, but I don’t believe her because her walls have sort of come down around me, and deep down she is a soft-hearted and very caring person. At first she was very distant emotionally…maybe that’s good, but then again maybe she would have fallen for any guy who would have given her the attention I did. I just don’t feel so special or chosen really.