Selfish to a certain level is normal. You are in individual with your own life and things like self care and self love are very healthy and ok boundary to be selfish in. Selfish that is toxic and crossing boundaries is more what bf is showing. Dependent and expecting others to clean up one's own messes and issues like it is their entitlement. That is the line of selfishness that would be unhealthy. So I won't call what you are doing is really selfish to that point. It is reasonable and it is great you are standing up for yourself and having high self respect. You are doing the right thing to priotize your mental health and peace. The problem is more of a them problem than a you problem so don't get gaslit or gaslight yourself. But it might be a sign of some yellow flags that could be borderline red. The lack of consideration and selfishness in their actions and behavior is a concern. Thats not very viable to maintaining a relationship and it might lead to ruin.