He's had 19 sex partners :(

Met a nice 26 year old online. We went on our second date and I asked him about his sexual history. He said he's been with 19 girls. That number seems very high to me. I've only been with 1 man. I feel uncomfortable and don't think that I want to eventually be #20. But I feel like a douchbag for not being able to accept him for who he is. Especially bc he's such a nice guy. He says he really likes me and regrets having such a high number bc he now has to tell me, a nice girl. He says he wishes he would have met me before all of them. Honestly this would normally be a deal breaker for me, but I've been single for almost 4 years and idk if I'll ever finally date. Idk what to do or think. Should I keep seeing him? I kinda like him but honestly can't see myself in bed with him knowing he's done the same with 19 other girls. 
To clarify, he put me into a position to ask how many partners he's had. He told me he was going to tell me whether or not I asked bc on the site we met, he'd seen a question I answered relating to this. The question was something like "how would you feel if someone you were dating told you they've had more than 14 partners." I answered that it would make me uncomfortable.