I'm so sorry you're going through this.

I definitely understand losing your libido. I was very lucky and didn't have to stay on the meds that did it for very long, but it was hell.

I also have chronic pain from endometriosis that makes it pretty impossible to have sex for a good chunk of the month. Oral is in there sometimes, but I know that's not an option for you and there are other ways I help my SO get off. Snuggling in bed and talking dirty while he gets off, handjobs (they don't have to be sad, my SO loves them lol, just get into it and play around), passionate kissing while he gets off, watching porn together if you're okay with that. You can still try to involve yourself in his pleasure for the intimacy factor even if you aren't feeling all that sexual.

Just tell him what you told us. You love him deeply, you wish things were different, but since this is the way it is, you appreciate him standing by you while you do your best.