Sounds pretty shit, but better you type it out than let it pent up inside you.
May sound obvious, so I'm sure you have already done so, but how about talking to your GP. They might be able to point you in the direction of someone that can help, or at least be happy to listen to you.
Perhaps another silly suggestion, but how much exercise are you getting? Are you unable to ride at the moment? (I get angry if I haven't ridden in a couple of weeks, but I realise your situation is completely different!) Maybe try some different types of exercise if you can't ride. Swimming? Running? Or even walking?