Best friends? Future relationship? Just fwb?

Kara
Okay hi. I need some advice. About three years ago I dated this guy for a couple months. We've stayed friends but this year at school we grew kindve closer...but he has a gf. Theyve been dating a month. Anyways, he asked me to be his fwb (but we havent had sex yet.) We just havent had the time or place. But we talk every day. We're close friends. But yesterday I could tell he was really upset about alot of things. He wouldnt tell me. All he said was hes confused. Then last night he said he loves both of us (me and his gf) & that hes loved me since we dated but he broke up with me then cause he didnt want to hold me back...then I asked him why is he still with her then, and he said that she calms him down...but he said she doesnt make him happy. But yesterday they looked pretty damn happy to me....idk he just seems more real with me....Anyways, what do I do? About everything? Is his feelings true? Do I be his fwb even with all of my feelings?