Husband wanting to go on a guys trip Mother's Day weekend

Me and my husband have 3 kids and they're all under 5 so they can't do much for me for Mother's Day. My husband wants to take a boys trip to see his childhood best friend. His best friend had contracted HIV when he was 17 from having sex for drugs. They were still close but since my husband moved away they just spoke over the phone but he is extremely depressed and has decided to stop taking his medication because he wanted to kill himself. He always had mental health issues and his HIV turned into AIDs and he's pretty much dying. They were in the same fraternity in college to and made great friends with their frat brothers and this is the only time they can ALL get together to see him in the hospital because he will probably not live much longer and my husband feels bad for not keeping better contact. I asked my husband why he can't just go see him on his own time some other time but he keeps saying this is the only time everyone can get together and see him. Idk how would you feel about him missing mother's day for this

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I know he's dying and I'm not trying to be mean but he didn't have to die. I know his life and childhood and what lead to him doing drugs but he got HIV from either sex with strangers or the dirty needles. Even with HIV he could have lived a long normal life. All he had to do was take his medication but he chose to stop. I know he has always struggled with mental health and I understand why he made the decisions he did. I had PPD so I know mental health can be a bitch but like my choices were my own when I had PPD. His are his own