Crushing on straight friend

Hi, my story is quite typical but I really struggle with it I’m 19 and I live in a homophobic country. All my friends are males and straight and I’ve never crushed on them. They are like my brothers. Also I’m in closet, nobody knows about my real sexuality In my uni I made a friendship with one guy. In the beginning there wasn’t something strange: it was like with all my friends But I started to know him better and then I crushed. Really strong. That’s so terrible. I just don’t know what to do with my feelings. I know that I can’t change someone’s sexuality. He has a girlfriend, they live together for a long time but I always have thoughts like what if he is a gay or bi in closet and etc, because he is so gentle, kind, sensitive…. Like he is in my situation, he can’t be open because of our society. Sometimes it really seems to me that he might be gay. But on the other side I can see how he looks at another women, I understand that all my thoughts are just what I want to be real, they are delusional. I just can’t handle it. And I feel like I do something disgusting, something disrespectful towards him. What I can do with this feelings? How manage with them? Will they just disappear?