I’m so sorry to read your post, and pray your husband is as comfortable as possible as he approaches the end of his life. I think I would wait to see if your BIL asks to come. If he does, then you could then ask him why he wants to, and maybe talk about it. There may be things he has struggled with that you simply don’t know about. However, if you’re not satisfied with what he says, I can’t see any reason why you shouldn’t say you don’t want him there. Then if he did just turn up, he shouldn’t expect to receive a warm welcome. Also, as has been pointed out, numbers may be restricted anyway. Of course, he may not want to come, and then you have no worries. God bless?