Hi! This seems like a time when maybe a break is needed. Even if its just a week or two. It seems the friendship has gotten to a point where arguments are starting to happen and chances are, will continue to happen. You feel awkward because you're just not used to having that staleness between you two. And this is probably a case of either something happened or something isn't happening.
In the friendship, think of something that has changed. Something that was present in the beginning but now isn't or faded a bit. Is it the excitement? Is it the connection between you two? You said he stayed with you and you stay with him, so maybe that energy is long longer there.
In the friendship, is there something that you want? Do you want more than a friendship? Don't just totally dismiss this. You said, "almost gay close." And that seems pretty strong to me. If you want something more and hes not acting the way you would prefer, then you would start arguing. And it would be over the smallest things. Anything would irritate you. So think about your feelings. You might find the answer there.
Leaving you for his ex could of been just an effect of the argument. It might not even be that bad. Have you attempted to just talk to him about it? Communication between you two will settle this. Get all your feelings out in the open. Leave it all on the table. Talk to him about what will work and wont work. And he can give you his opinions too. This isn't worth losing a friend over. But this could be just a rough patch. Maybe hes going through something you don't know about. Talking to him will find all these answers.
Best wishes, and PM me if you want to talk.
~jamesish~