I mean is your bf the type of person who judges people by their families? Is he from a culture that holds family "behavior" or "appearance" in high regard? If he's not then this feels like your own shame over your father's behavior spilling over into anxiety about what other people will think, when I think most sensible people would see that and go "ah what a shame your father is a jerk, must've sucked for you" and wouldn't use it to judge *you* as a bad person. You're not responsible for your father's bad actions. In fact it seems you condemn those actions quite consistently and seriously. Why not just open up to your boyfriend, since you say it's a "serious long-term relationship." So what if he sees that your parents are dysfunctional? As long as the two of you are treating each other well and it's not affecting your relationship, all it does is give him a little more information about your upbringing and in fact could be helpful in the future for giving you both context to be better communicators.