My parents are a nightmare!! I need advice please!

For context, I (14f) am half french (dad's side) but we live in england, but I'm not fluent because my dad refuses to speak french around the house, however I do take independent online lessons (by choice) and I do french at school. Recently, my dad's french friend got married. The wedding was in Australia but they had a party in France for people who couldn't make it. My parents asked if me and my siblings wanted to come; I didn't want to at all as I always feel very uncomfortable whenever we are around all of the french friends. I made this clear to my parents and they were fine with it until the day we were supposed to leave and they said "pack your bag, you're coming". I was annoyed, but complied.
I am not antisocial at all - I have great friends and I get on well with most people and I love parties and big events. I also have a passion for drama, performing in the west end musicals, I've been in movies and series and I've been doing drama for 10 years. But when we are around the french friends, I feel so uncomfortable - I hate the kisses on the cheeks, the cliques and the language barrier. My parents said if I really didn't want to stay at the party, I could leave in the evening and go back to the hotel (10 minutes walk away).
I really did try to enjoy the party, but my parents kept telling me to look less miserable and that I don't have any social skills and they kept bringing people over to introduce me...usually old men that my dad was friends with and they would do the double kiss and I hated it so much! They said I could leave after dinner, so I asked what it was and they said chicken curry.
I am vegetarian, by choice. I am very anemic, but I take plenty of supplements, so it's not really an issue. I hate all meat, it's just gross; and I also am a firm supporter of animal rights. My parents know this but completely ignore it. They'll make one meal always with meat and force me to eat it even when I offer to make my own food. So when it was chicken curry, I said that I would happily go back to the hotel and make my own food but they forced me to sit down and eat it.
When I was about to go afterwards, my parents were talking to french friend whose part it was. They were saying how I was so antisocial and rude. They then called me over and said to me, "why don't you stay at the party, it'll be fun!", trying to guilt trip me into staying, in front of the host. I was at the end of my tether! I have always said that I had hated this sort of thing with the french, and they pushed me and pushed me and pushed me and I was so angry, I just stormed away. Back at the hotel they were yelling at me, saying that I embarrassed them and for someone who likes drama, I suck at confidence, and that I will have no social skills and will die alone.
And it's not just this time. All my life my parents have emotionally abused me, playing with my feelings and guilt tripping me; mentally abused me, my mother frequently comments on how my stomach is too fat (it's not - I am actually underweight and slim), how I should look a certain way and regularly comments on how I always look depressed (I struggled with this severely, having to get counselling behind her back); verbally abused me, hurling insults and criticism, always making me feel bad about myself, victimising themselves; physically abused me, they slap me round the face and sometimes on my behind (which is so inappropriate, given I am a pubescent teenager on her period!). They always gaslight me when I call them on all these things, they tell me I'm stupid and I'll fail in life and that I'm so ugly that no one will want to marry me if I accuse them of such things.
Please! I need help desperately - advice on how to deal with them?!