Oh your poor son. It's so hard being a teenager and anything that makes one 'different' can cause so much anguish. I'm so glad he has a lovely mum to support him, and some great pals around him too.
I don't have any particular advice but I do want to offer assurance about what his life will be like when he's older.
I was a nineties teen and when we were 14 or 15 one of my closest friends (we'll call him Fred) came out as gay. I wasn't surprised, and his family were hugely supportive, but in the mid 90s this was shocking for many and Section 28 was still in full swing. Fred got a lot of shit at school - name calling, constant comments etc., not just because he was gay but because of how he dressed and that he wore make-up occasionally. And if wasn't just the kids, but the teachers too. It was horrible. He was the only openly gay person at the very large, nowhere town, comprehensive and it was bleak.
We both moved on to a sixth form college at 16 and suddenly most people (not all) didn't really care that he was gay. And then a few more people came out over the two years we were there - some of them said that Fred being so openly gay gave them confidence to be themselves too.
I'm still friends with several of the people I met at that time, including Fred, even though we've all moved away. Fred and a couple of the other gay lads I knew then have all thrived. We're all well into our 40s now and they all have great careers and lives. One is married and he and his husband have adopted two kids; Fred lives with his partner who he met at uni; another met his partner online dating about a decade ago. And none of the lads have (as far as I know) ever been physically attacked.
Having quite a a few long-term gay friends means I've then met many of their friends (and I have known/worked with many more gay people) and I'd say this pattern of success and happiness is repeated across most people I know who are gay. That is: they live lives not much different from many straight people. It perhaps helps that I (and many of my friends) now live in a major city that prides itself on its gay-friendly nature. But, like I say, we grew up in the 90s when social attitudes to homosexuality were about a million miles from where they are now, when newspapers 'outed' people on front pages and people still associated homosexuality with AIDS - which had been known as the 'gay plague' by many. It was shit.
Of course homophobia is very real and gay men (and gay women!) still do get attacked or verbally abused simply for existing. But that's not the daily reality for most gay men.
I just wanted to share that out of the darker days of the nineties so many gay teens blossomed into wonderful young gay men and now into fantastic middle aged gay men who are happy and living rich and varied lives. Whatever your son wants to be, he can be. As he gets older and grows in confidence and leaves the twatty little bullies behind he will flourish.
I hope he can see beyond the next year or two and beyond the headlines. There's a reason why homophobic attacks (rightly) make the news now. They're fortunately quite rare and absolutely shocking to most.
I also hope you get the support you need to help your son through this very difficult stage in his life