For context, I have a friend, Corbin (not his real name), and he is the best friend I've ever had. I have Autism, which makes it hard for me to make friends. When I met Corbin at my job, we kinda clicked and became fast friends. Turns out, he's also Autistic and has no friends except for online. We became each other's best friend and for the first time in my life, I had a friend that I knew would never leave me and would love me no matter what. However, Corbin has been struggling with depression for a few years now, and a recent incident kinda pushed him over the edge. We were making plans to hang out in a couple weeks, but today Corbin texted ne and said we probably won't be able to hang out. He said he's going to a mental hospital to get help, and he'll be there for 4-6 weeks. I've already had a shitty week, and without realizing, I got angry and told Corbin "Great, because this week wasn't bad enough." He came back with "Well I'm sorry that me getting actual help interferes with our plans." When I read that my heart sank and I knew I fucked up. I messaged him profusely apologizing but he won't respond. I'm afraid I've messed up my only true friendship and IDK what to do.

TL;DR I acted selfish towards my only friend and now I don't know if he wants to be friends anymore

Update: Over the time that my friend was at the hospital, I was messaging him support. I didn't think he would see them because he probably wasn't allowed to have his phone, but I messaged him regardless. Well the other day I noticed that he had seen a post I sent him on IG and changed his pfp on Discord. So I messaged him asking how he was doing and that I wanted a response because him ignoring me was unbearable. This morning I wake up to a text saying he doesn't want to be friends anymore. So I guess me slipping up once automatically invalidates everything we've done together. I just want to curl up and dissapear.