Y'all I need help.

So long story short I met this guy a good 2 months ago and we totally hit it off. he was super nerdy about the same stuff as me and hilarious and generally an awesome guy. So I start talking to this guy on a regular basis, my boyfriend at the time gets super jealous (which I can understand) and I end up dumping him (ultimately a great decision, I realized how headstrong he really was after the fact). I find out this dude I've been talking too a lot HAS A GIRLFRIEND and even worse, she was a friend of mine a long time ago who I just fell out of touch with. And so I keep talking to him until it gets to the point where we're talking over the phone for a good 3+ hours at obscene hours of the night. Which correct me if I'm wrong but I feel like that's not TYPICALLY something guys with girlfriends do with other girls. So not only have I completely fallen for this guy, but he keeps dedicating a lot of time to me which sends the "I'm interested" signals to my brain. I ultimately decided to just text him saying "hey man I need some time lets stop talking for a bit" just so I can figure myself out but honestly I already miss him and it's just making me more angry at myself. That and the fact that the thought "oh I'll just wait for him to dump his girlfriend" has totally crossed my mind and that's not okay. Basically I need some advice y'all. I don't want to be the reason that anyone ends their relationship, but at the same time, I've never met a guy like this.