possibly bisexual/demisexual falling for straight roommate/best friend

Hey guys so, I'm an exchange student from England (actually not British though, so sadly, no hot British accent)and my roommate is also an exchange student from England but we come from different universities and met for the first time when we came to America really.
I've always known that I wasn't a 100% straight, Im a virgin still, mostly because I don't want to go there if I'm not sure of my sexuality (although some could argue that that's how you find out what you like). I've only ever kissed, and for the girls I have kissed, we either dated or had feelings for each other. I've kissed two guys, one was just to try it out, and the other one was by surprise-ish, he kissed my neck for a good 30 seconds before slowly making his way to my mouth and till this day, I have not had a better kiss.

When me and my roommate, Alex (not actual name) moved in, we got along really well from the get go, and I was relieved that I wasn't sharing a room with someone who I didn't click with.
I didn't have much luck here in the US and had bad thing after bad thing happen to me (mainly prejudice and racism, I'm South American) , my roommate was there for me through it all, and I would cry and he would hold me in his arms until I settled down. This happened three times before I realised my feelings for him kept growing strong, strong to the point where I can say without a doubt that I'm in love with him. He isn't gay at all I'm sure, he is very open minded though and prides himself in that.

I call him baby for everything, and he has added baby to the end of my usual nickname (which has actually caught on). I caress his belly everyday at least once, he has very soft skin and really thin blonde body hair, so I love caressing his belly and playing with the hairs on it. He says I'm weird but let's me do it. He is flat footed (it's a condition?) and I love giving him my version of a foot rub - I just caress it and squeeze and play with the hairs, yes I'm weird - and he actually loves that and says it feels quite nice. He has asked me on a few occasions to do it.

Everyone says we have the cutest bromance ever, he puts his arms around my shoulders when we're walking. During spring break a couple of us travelled to Miami , and I shared a bed with him, I'd wake up and caress his belly, but this time I went a step further and worked my way to his chest and slowly caressed him as we lay in bed. He was awake btw, and didn't tell me to stop or move away or anything. I did this pretty much every time I woke up next to him.

He has a girlfriend who loves our bromance ironically. I have seen him naked and his dick is huge, I'm not attracted to gender or sex at first, but because I have this bond with him, I would actually go down on him or something.

My big problem with it all is, I'm leaving in 28 days, and loving him hurts me so much, that I just want to disappear off his radar once were back in England, we live in complete different parts of the country anyways. He has expressed his wish to come visit me where I live, and his parents adore me and want me to come stay with them for a while.
But I don't think I can have him around anymore, living with him is torture, although he is lovely and I love him. At times I see him and his girlfriend, I'm happy for him, and her, and I feel like I've reached a point where I've let go and moved on, but something happens, a hug, a stare and it all comes back. He recently kissed a guy at a party, which he says he's glad he's done it because it shows how progressive he is etc... But I remember seeing the snapchat on my phone, and just feeling, betrayed? Is that weird? Am I losing my mind?

He has invited me to stay with him at his university house and even said "it's a double bed, it can be like Miami". Should I drop him as a friend for my sake, or should I have an honest conversation about it (I don't want him to leave his girlfriend for me, I'm not delusional), I don't think our friendship can go on if I don't let him know where I stand, otherwise I feel like living a big lie, and having to force myself to be his friend, which I don't think I can be. How do you stay friends? I haven't loved anyone like this in a long time and I'm afraid it won't leave me.