Weirdest events ever... what to do?

I think i'm really crazy because i'm asking help from a lot of strangers now.. but i might get some advice i need.A few weeks ago a met this guy at work, he started working at our company and from the day he started working there i felt he was handsome, but i didn't know him. So the next day (his second day) i send him a chat message on our internal chat system. A pretty normal conversation about what he was going to do at the company and if he liked it till then :) Nothing weird. But a few hours later it was a very, very active conversation about almost anything, music, his ex-girlfriend, my ex-boyfriend etc. It really was a relaxed and cool talk. Because we were talking a lot about party'ing i invited him to join us (me and a bunch of colleagues) to head to a pretty cool party later that week. He was fine and he liked it, so all said and done. That friday we went to this party, and a few colleagues(friends) had some drugs, so we used a bit both and the party was pretty fun, until the drugs hit me in the face. I panicked and freaked out very much. I ran out of the club because i needed fresh air and he followed very quickly. He could see that something was very wrong, my heart-rate was almost losing it and i stopped breathing normally. That when things started to get weird, he was very kind, giving me kisses on my forehead and saying that everything would be fine... We got home (which i don't remember) and crashed in my bed. When i woke up the next morning because i was thirsty he was very close to me in my bed, his arms around me and hugging me very intensely. I thought it was the drugs, so i didn't think anything was weird. When i got back with my water and dropped into bed again we were hugging again in matter of a few minutes.The next evening he stayed over another night, because i was still feeling very weird. Then it really started to freak me out. I woke up in the middle of the night because he turned around in bed and moved his arms from his side of the bed to my side, and started hugging me. I felt pretty happy with it, until he started going down, to my chest, belly and kept going lower until he reached my boxershorts. He started playing a bit with my boxers and i didn't even had time to realize but within a few minutes we were "doing things".Could have been curiosity but the relationship only got more close. Talking about literally everything and seeing each other very regularly at my home or his home. The "bed thingy" happened a couple of more times, and now he added kissing to the list of what happened. I'm really confused because i'm really liking this guy, but the weirdest part is that he still says he is straight. He says it is very very interesting and he likes it a lot, but he does not have any feelings for my or any other boy. Today he added the sentence : "I cannot assure you i cannot fall in love with you, because everything that already happend... i don't know. It might happen", but he is vague to the max. To make it every more weird : His ex-girlfriend (they are still living together) told me she just KNOWS he has some feelings for me, but he doesn't dare to tell me because either way he is very confused or he is afraid of the reactions.It's driving me almost crazy, because i want to be with him (and he wants to be at my place all the time), but he says he is straight... What should i do??