You may not have lost him as a friend for good but just after you break up it can be difficult going straight to friends (its difficult anyway!) When I broke up with my ex I hoped we would have the same close friendship we had before we went out & during our relationship. It didn't really work like that. We had moments of being close but he doesn't let it happen very often. I think its cos hes got a new gf who is his priority now & also cos it confused his feelings when we got close. Your ex may find it hard to be close to you cos it stirs up feelings, even if you know it was right to break up you can still miss what you had. Also sometimes it feels like you haven't broken up which confuses your head a bit.
I know this doesn't really help you much at the moment cos you need a friend right now, I completely sympathise with you. I went through a rough patch after I broke up with my ex where I really wanted to talk to him about it & couldn't cos he was completely ignoring me. But it may well get better. Give it some time. When you get back from holiday you may find you both are more clear headed after the time apart and can be friends. In the meantime I know its hard but try not to feel too down if he doesn't contact you. I don't suppose its that he isn't interested, probably its just his way of working through things. Hang on in there! Maybe see if there is anyone else you can talk to. & remeber you will in time find another close friend you can talk to, its hard until you do but it won't be like this forever.
These A-levels give you the most options