Might be falling for coworker, but don't want to. What should I do?

I am a gay 22 y/o man who had a crush on one of my coworkers who was straight a few months ago. I told them, and then moved on. The problem is now that a new guy started at my job who is around my age and we work in the same department, and I'm worried that I'm starting to develop a crush on him.

He and I came quick friends the last couple weeks since he started, he is always trying to be around me and constantly acts flirtatious with me. He tells me how good looking I am, he has hugged me, and always makes jokes like if we were in a relationship.

I don't want to put myself in the same situation like I did with my other coworker. I don't want to fall in love with someone that I can't have and be hurt again.

So my question is this: He and I don't know each other very well yet, and he doesn't know that I'm gay. A few days ago, he asked me why I didn't have a girlfriend? He told me that he has one, but he never really talks about her that much. I'm guessing because he and I don't know each other that much yet to talk too much about our personal lives. How do I kind of hint to him that I need some space without it seeming like I hate him. Should I just honest with him about the situation? I'm just not sure how he is going to react when I tell him that I'm not straight; Any advice on what I should do?

Thanks!