I know that your bf sometimes doesn't "get" the interpersonal stuff very well, but ... I found it really helpful when my Dad was sick to put my husband between me and my parents as a buffer. Maybe your bf could play this role in this situation for you too. For example, my dad knew how fragile my mother was emotionally, and I guess he always made it his #1 priority to take care of her. (I think this is how he loved her for 50 years despite her narcissistic nonsense ... he perceived clearly that she was fragile and needy and treated her as such). So when he was told his arm had to be amputated because of the cancer, he came over and said YOUR MOTHER is going to need you. I heard that giant sucking sound H. Ross Perot used to talk about ... I was going to get sucked back into too much closeness with my parents and I was terrified. Yet, I knew that Daddy genuinely needed me and I genuinely loved him and didn't want to let him down.
However, when he first said that i just froze. I probably turned white as a sheet. Not because of the awfulness of having his arm taken off (although that was bad enough) but because I felt a "soul amputation" coming on as well. My hubby, bless his heart, stepped up and assured my dad that HE AND I would always be there to take care of them (my parents) and that we would do anything they needed done. What a relief it was. They could be supported but it didn't have to be just me ... and my mom seldom gaslights my husband, I guess she's kind of in awe of him or something.
I mean, I knew that he was going to be there for me anyway, but in that situation I felt like my parents were using this terrible circumstance to reel me back into their dysfunction. He kept that from happening and was able to love my dad and help him through that terrible time. In fact, a year later he sat up with my dad all night, the night before he died.
IMO, it's not only OK, it's a blessing if someone can be a buffer.