Wow!

If he's genuine in what he says, recognising that he has a problem is half the battle.
I think 'wait and see' is probably the best approach, and don't get your hopes up. But I'm wondering; if he does have strong feelings for you still, is it worth making a relationship with him the 'prize' - asy you've already started to? Ie. yes, I would like a relationship with you ONCE you've got your head straight?

I'm also wondering (but very cautious about this bit) is it worth being freindly with him whilst he's working through this? Maybe again treating it as a bit of a reward - he gets to see you for half an hour AFTER he's been to the psychiatrist?

Dunno. Others may have better ideas. I never experienced this either - he's been constantly negative.

Fingers crossed for you - I hope he's one of the few who does work out how to 'manage' it, in which case he deserves a medal!