Some thoughts about my girlfriend's sexual past

[Joods]

My girlfriend and I were watching some romantic comedy the other day (not my idea, trust me), and the topic of sexual history came up. So we ended up talking about it, and it turns out that she's got quite a past.
She's 27 and here is just some of what she told me...
Her first time was when she was 17
When I asked her how many men she's had sex with she couldn't tell me but when I asked if it was over 20 (jokingly) she said oh yes, way more
The first time she did anal was at the age of 18
She has had a threesome on 3 separate occasions
She has kissed girls in clubs many times
She was a member of fetlife for a couple of years
She mentioned something about doing porn
Those are the highlights but she mentioned quite a lot of other occasions and people.
This is not OK. I've been with her for 3 years and I had no idea about any of this. I always had a feeling about her but I really didn't think it was like this. This is a huge shock to me and what bothers me is that I've invested 3 years of my life with someone whose values and mine most certainly do not gel.
I don't really want to break up with her, but at the same time I can't imagine staying with her and being OK with this. It's going to nag away at me, I know it. I'm a firm believer that her sexual history has a lot to do with the ability to pair bond (or should I say, the inability), and I have seen enough evidence of this with my friends and their girlfriends to confirm it.
I hate to think about it as 3 years is a long time, but I guess I probably will be finishing with her, at least that's how I'm feeling right now. But I just want to get people's opinions, for what it's worth.

A few things...
I didn't read anyone else's posts before posting this. That said...
A lot can happen to a person inside of 10 years.
People are human and do stupid stuff in their late teens/early 20's.
She's put up with you for 3 years. I'm sure your past isn't perfect and obviously she's matured enough to be in a secure, steady and stable relationship for this long.
It's been said that the 20's are all about finding one's self.
Most important: Her past is her past. She doesn't live there anymore. You shouldn't hold that against her especially since I'm quite sure you've done stuff in your past that you probably wish you could take back.
Ultimately, you are going to do what you want to do and having the opinion of strangers really shouldn't be a consideration. You have to live with your decisions. If you feel that after three years of putting time, love and energy into a relationship with a woman who has obviously grown up (she's dating you after all), doesn't sit well with you, then perhaps you need to examine your own faults and shortcomings before judging another. Clearly, in this day and age, talking about prior partners and the possibility of STD's should have been a factor (you know, because of YOUR values and whatnot) before you decided to enter into a long term relationship with her.
I'll end with this:
People who live in glass houses shouldn't throw stones. Unless you have a perfect record of having never done anything stupid in your entire life then in all honesty, who the hell are you to sit in judgement of anyone else?