Comments

Sorry if it sounds like I am defending your father's girlfriend, but of course she would feel that way.  I would feel that way if I were in her position and you said that.  I probably would not break down in tears, but I would still feel confused, and I would ask "why did he say that?  Does he just want some father/son time?"  Did you talk to your dad about it?  Again, a thing is, we are all selfish in the very end and are always trying to get what we want.

Why did your dad's girlfriend get emotional?  Well, probably because some people are naturally more shy and sensitive than others.  Women are often more emotional than men.  You made her feel unwanted and confused.

So talk to both of them about it.  As for your dad ignoring your plans, that is what parents do.  I am in my forties, dad is in his eighties, and he still does it to me.  It is frustrating, I know.  But talk to him about it.  If you tell your father, "Dad, I don’t think your girlfriend is a bad person, but I really wanted some alone time with you," he will understand.  He will feel needed and get emotional in a positive way.

I can see both sides. I am quite an emotional person, so if I was in your dad's gf's position I would've been upset too. But knowing that you have a personality disorder and bad parents makes your reactions/responses understandable. Tone also matters a lot, you can say 'why is she here' in both a rude way and a curious way, and judging by how you emphasized she, it was the rude way, which probably lead to her crying. And the fact that you said it in front of her is more rude too. 

I would suggest to try an not let these small things like a change of plan affect your mood/tone too much, but I'm guilty of it too sometimes. I'm not trying to be mean here btw, just stating my point of view. I can't say much about you mom, though, don't have much experience with that kind of person. 

What do we do with this now?