Is it weird to want to stay in touch?

TLDR: I'm graduating and I want to stay in touch with my teacher who has had a profound impact on me. The post is kinda long, sorry. It's quite detailed and kinda venty. Do you think he will agree? And could it potentially become a friendship a few years down the line?

OK, so I'm in my final year of school (18F) and I really look up to my English teacher (32M). After I leave, I'd like to stay in touch with him because I would never admit it to anyone irl but I'm going to miss him a lot...don't worry, I don't have a crush on him...I did at first but now I see him like a cross between a mentor and a slightly estranged older brother, I suppose? Idk how much sense this makes lmao...but he was the closest I've ever come to someone understanding me. I'm very perceptive and feel deeply, and I think that I remind him of himself sometimes.

I opened up to him about some stuff (parents splitting up, bullying, etc) last year but I think he got in trouble for not going through safeguarding processes. When he did eventually tell my head of year (who he knew I don't trust), I felt betrayed but I knew he was just doing his job. However, it later clicked that he had felt overwhelmed. So I apologised just before the summer, and I was crying and I said 'I was just telling you all my problems, and you were helping me with all this stuff, and I just wanted to help you too. All I ever gave you was a pack of pens and telling you to stop being self depreciating.' He looked like he genuinely wanted to hug me, like he was full-on looking at me like a person as opposed to a student. And at the end of my little yap he just quietly said 'I'm moved.'

Flash forward a few months, our conversations are mainly just small talk. I feel like I can't really talk to him about anything on my mind because he'll tell the head of year, but I know that's kinda what he's meant to do. I have big trust issues (not here because you don't know me irl lol) so I suppose when I've opened up to someone, I've been really selective about it and I end up caring a lot about that person. And I was never angry at him even when I felt betrayed.

I'd like to stay in contact with him, and I'm planning to give him my email when I leave. I'm not going to treat him like a therapist or anything, but he's the closest thing I have to a friend at this school and I suppose I'd just like to see how he's doing from time to time. Based on everything I've said, do you think he will likely agree to keep in contact? I'm going to ask anyway, but I just want to know what others think. Also, could that ever evolve into friendship/meeting up for coffee in like 5 years? I'm aware it's not a guarantee, but based on what I've said...

Also, at my school there are quite a lot of teachers who were taught by others working there. Eg: my history teacher is married to one of the english teachers and both were in a class with my head of year and all three were taught by the headmistress. 

Also, I win a lot of comps and he seems genuinely proud of me on a personal level if I tell him. He calls me dude/mate as well sometimes but it's not just me. However, as said I'm very perceptive and I've always cared more about him more than he cares about me, even with the professional walls. But like, he has a wholeass wife and little siblings. I'm some kid in a class of 10 who might not even matter next year.

Maybe I should worry less about all this, because what will happen is meant to happen I suppose. The first time I ever opened up to him about something, he said 'you don't have to be atlas.' Basically, stop worrying about stuff and trying to be there for everyone to the point that you aren't there for yourself.

Thank you so much for reading, I really do appreciate any advice or comments.