I think for now its just a matter of waiting and see what my line manager says but I have to say if this carries on I will start to talk to HR about it because as mentioned I feel isolated and in a way this is a form of bullying. If they think they can just walk over me they got another think coming.
Join a minority, many come with immunity from almost anything.
DO IT!
If you go to hr and they ask when it started say something innocuous but try to let it slip that about the time one of them found out you where gay they all started acting this way