Sick partner need advice

Hey sisterhood, this is a little long winded so please bare with me.
I have 4 kids from previous relationships (2 teens & 2 under 10) with me pretty much full time. I am no longer fathers and I have had a new partner for the past 2 years. He is an amazing partner and role model to my kids, he is very understanding of everything and helps us out in anyway that he can. We don't currently live together but was planning to when certain things have been completed with my house for him to move in. Anyway, we recently found out that he needs to go on TNF treatment for his autoimmune condition, which is effectively going to get rid of his immune system. The problem with this is he feels horrible for me and the kids and having to put us through him being like that. If we get sick we could end up putting him in hospital if he catches it. I guess what I am looking for is advice, has anyone ever bee through something similar? Can you make a relationship like that work? because I am gutted thinking that we cant find a way, like I'm more upset about this then what I was separating with my over 10 year relationship. What are peoples thoughts? Good or bad? Am I being selfish for thinking that I can make something work? We both want to be together it is just is it actually going to happen or will it just result in us hating each other?