Don't do anything that makes you uncomfortable. Never go against your own judgement and self for any man.
So, are you going to put your whole life on hold while he goes through therapy?
Depending on why he's attending therapy, he could be there for months, maybe even years. Normally when people go through a breakdown, they don't come out the other side the same person they were before and you have to prepare yourself for the fact that he might not want the life he had before.
Breakdown or not, he's left you and expected just to cut you off unless it suits him. That's extremely unfair not to mention cruel. It's completely one sided and selfish.
For your own sanity I think enough is enough. You've done what he asked and backed off and it's destroying you. Now you need to tell him that it's time to talk. You need to sit him down and ask him once and for all if he's coming back so that you know where you stand. If he says no he isn't coming back, then you at least have an answer and can finally move on and rebuild your life. If he refuses to talk to you about your relationship, then you still have your answer.
By waiting around for him you're adding to the hurt and pain you're already going through, which is doing you absolutely no good. You need your answer now as clear as day because the not knowing is crushing you.
You can get through this. But it's time to ask yourself the tough questions. Do you really want him back? And if the answer is yes, can you trust him not to hurt you like this again? Can you live with the uncertainty?
Please, for your own sake take back control of this situation.