I don't know what to say?

Ok so like I kinda slapped my girlfriend in the face earlier today becus she kiss one of her friends(female) on the cheek ok so the first time it was w.e like ok but then she goes in a second I'm like yo wtf r u doing stop so she continue so I kinda slap her w.e n it hurted her so later after school she told me to wait for her dad..so I did n ago when he come I'm like baby r you serious..she like nah man I don't wanda here that..so then she tell her dad so her father walk up to me pissed n punches me in the face..let me mind you I'm 16 not built lean n this guy is like in his 40s so I was suprise them his daughter see that he still walking so she drop her bags and attemp to stop him, at one opine when I was backing away she tell him daddy stop that all I wanted..thus he tells her to go inside..so I go home pissef then later this day I cal so her moms picks up n ask me what's my problem y I'm hitting ther daughter for no good reason..so I start saying sorry forgive me I won't happen again..then she says oh that's what you said last time cus this would be the 2nd time I've hit her..the mother then tell me that she very disappointef in me that her husband is very angry at me n they don't know what they should do about me..to conclude the mothers tels me that monday she going to the school to talk to me i seriously don't know what I'm gonna say..also not to mention her father talked to me a week ago about if I do anything to there daughter that ima get it..n I promise him I wouldn't thus idk what to do cus the father doesn't ever was see me again I believe n I really love her alot..n btw I told my girl that I don't like when she acts kinda gay..i was like of you did it the first time ok them y would you go again the second time she said oh becus if it nothing wrong n you know I'm not gay then y is it a problem..ppl help plz srry for all the info