Need advice: boyfriend has changed a lot due to depression

Hey ladies I need some advice.

I’ve been with my boyfriend for over 8 months now long distance. We became official on our first vacation together. After that we would constantly talk on the phone almost every days. He was so sweet and we had great conversations. Over time everyday was to much. We started chatting 3-4 times a week over the phone plus we got to visit each other every 1-2 months. Him and I both are going through some mental health stuff with depression and all that. He has become very grumpy the last month. He has made it very clear he hates talking on the phone. When we are on the phone I’m basically talking to myself. He completely zones out and isn’t involved in the conversation. He’s also become very rude and snaps at me a lot. Then some day’s over text he can be soooo sweet. He picks fights a lot it seems like over little things. We talk about once a week on the phone now. I’m slowly becoming more distant I’ve noticed(its a way of protecting myself) and occasionally he notices it to and gets mad and freaks out. He gets scared when I never ask to talk on the phone anymore but I don’t ask because I know how much he hates it. Then when I do ask to talk he gets irritated.

I’m trying so hard here. I know he’s depressed and how much it sucks. That’s why I’m in a partial hospitalization program myself for it and for anxiety. But I try and make him as happy as I can by not “bothering”him as much (as in texting to much) and giving him space. Everything he asks for. I also do know he is acting this way because of his depression because he used to be the most amazing guy and he actually enjoyed talking on the phone.

I would like to express to him that chatting on the phone is what helps support me through my metal health stuff and the long distance especially since I support him as much as I can and since we won’t be able to see each other for at least another 4 months. It’s not that I even want to talk every day, I just want a normal interactive conversation at least once a week. I’m worried if express this to him he will just freak out at me.

Also are there any other ways I can support him? I definitely feel like my emotions are not important at all in this relationship right now but I’d still like to support him the best I can.