Should i meet up with him even though he has a girlfriend?

A guy that I had a fling with a few months ago wants to meet up with me again. But he has been dating a girl for two (almost 3) months now. But he wasn't seeing anyone when we met first time around. He said they are serious about each other and that they both ‘love each other’. So why does he want to meet up and have with me?? I really think that I am in love with him. I’d do anything for him. He’s so good looking and he has a lot of female admirers. He asked me to go out with him a few months ago and I said no because I felt I didn’t trust him. And now I am glad I have made that decision because I felt he wouldn’t make great boyfriend material. But I still have feelings for him. And I cant change that even though I wish I could. I can see he is a player but that doesn’t change my feelings for him. The time we were apart which was a few months I could not stop thinking about him. I thought about him every single day. I’ve been with other guys since then but I don’t want them or care about them. I only care about him. I’ve never felt this way about anyone else before. And I find myself so much happier now that we are back texting each other. He sent me a text message yesterday saying ‘I think I love you’. I was so happy when I read it. The happiest I’ve been in a long time. I’ve been through a lot lately with another guy I would really just like to be with someone rather than be on my own. I really wish people would not judge me so harshly if I was going to meet him I would have done so already. I was suppose to meet him today after work and I didn’t. And I don’t want to hurt his girlfriend even though I don’t even know who she is.