I discovered his flirtatious comments on various girls' profiles? Help?

I met him online off this music site and he flew down twice to see me.

I recently discovered some flirtatious comments of his on various girls' profiles. They're fairly old comments though, but some are still fairly recent. Stuff that said, "<3 hey babe I miss you." "this girl is a hottie and I busted her cherry. props to me." and he would always chat up 18-20 year old girls on that site. They're pretty hot and love to flaunt alot of skin. Plus I suspect he met up with a chick because I found her on his facebook, and she lives closer to him and she was on his GUEST LIST for his 28th BIRTHDAY PARTY. She's super gorgeous :(

But I also don't doubt that he genuinely loves me. We have amazing chemistry, and laugh and talk about everything. He respects me and has told me numerous times, that I'm the only girl he wants. And that he won't ever stop pursuing me unless I give him a chance. (He's been pursuing me since 2008). On my birthday he rang and told me, "I'm actually kind of madly in love with you." "I think about you every second of every day and care about you more than anything." "I'm never gunna go away cause I love you and I've never ever felt this way about any other girl." "I don't say sh.it to you that I don't mean with every fibre of my being."

I dunno what to believe. I'm really upset though because I feel like he's just using that music site to pick up girls and that I'm just one of his "toys".
Do you think I'm over-reacting? Should I avoid him?