SO's depression, looking for advice

Seren • 26, UK

My SO is dealing with a bout of depression., and I need help knowing how to support him.I have suffered severely with anxiety and he has always supported me, so now naturally I am trying to do the same. The problem is that he is treating me terribly. He is rude to me, won't prioritise me, and is being so selfish. Every time I'm hard on him about it I feel awful because I'm supposed to be helping him through this. How do any of you guys help support your SO's?! I feel so lost and helpless.

All and any general advice welcome! but if anyone's interested here's what's going on:

We've been living together for 3 and a half years, and he's decided that being here where we're cut off from our old friends is not helping him to get well so he is moving away to live with friends. I can't leave because I just got my dream job here. He's essentially trying to re-create his student days and I'm having to give up our nice home and move in with my mum so he can do that.

Although it's sad I understand and am trying to make it work, but all I asked was that when we do make plans to see each other we stick to them so hopes aren't built up, and to be accessible by phone. He's been gone one week.

Our first night apart I had some bad news and was very upset, but he disappeared until 5pm the following day because he had gone out drinking!

Then he was due to come home on Friday night, and I'd been so looking forward to it it really got me through the week, and I bought dinner and everything, and told me Friday afternoon that he had forgotten and wasn't coming. And he wasn't sorry. I was upset, and he told me that it was "the bottom of his list of priorities" which broke my heart. Should I just accept and forgive and be understanding that he's in a bad place or should I put my foot down and demand more respect?