Dealing with partners mental breakdown whilst struggling with my own depression

I’m at a loss. My partner of 11 years has been struggling with poor mental health for years, but it took a turn for the worse about 6 months ago, and he ended up being sectioned after multiple attempts at taking his own life.

He was allowed home and things have been..ok. We’re taking things one day at a time and we know it’s just baby steps for now, but trying to support him is really taking its toll on me and my own mental health. I feel absolutely so awful and so so selfish for even thinking this way, honestly, I know it’s not about me right now. I just don’t know how to cope.

His medication ran out yesterday and he had slept through the day until it was too late to collect the new prescription. We had an awful night, with him extremely worries and having anxiety attacks every hour or so. I am trying my best to be a rock for him, but I’m just so so exhausted and my depression (that I had been managing very well for years) is starting to creep back in rapidly. I can’t turn my back on him now, but I feel like I am going to end up having a breakdown myself if things continue this way. Tonight he told me he was feeling very upset, and I, without thinking, snapped back that “that makes two of us” and it obviously made things so much worse. I feel like I can’t really tell him how much of an affect this is having on me, but at the same time, not telling him is causing outbursts and that’s not helpful either.

Please, if anyone has any advise on what we could do to get through this, I’m open to suggestions.