I'd like to give you a warm welcome here to the Forum, where so many people have gone though hard times there is no judgment, just a desire to share and help. You will never be put down here or have the feeling others are disappointed.
It is one of the sad facts of human nature that if you are constantly put down, feel an object of disappointment, lead to believe you not as able as others and most importantly are starved of the praise everyone needs then you start to believe all those things, and judge yourself harshly, feeling less worthwhile and having nothing to offer.
OK, so in part you have coped by eating. This is a pretty usual thing and there is even an organisation that is set up just to help. It's called the Butterfly Foundation and you can phone their Helpline (1800 33 4673.) or webchat or email for advice and assistance - they are very used to your situation
Being so down you can't complete your driving lessons, feel less able than others, cry by yourself and get to feel the things you are good at are not worthwhile is a horrible way to live. It is a real shame as life can be so much better. Your parents were silly, if the gave genuine encouragement to you and to themselves as well they may not be thinking of a split.
Your parents possible split will mean you need to be able to cope in better ways, and I realy think you need a had to do that. Have you heard of the Kids Help Line (1800 55 1800)? They are very friendly, and very competent, and not prone to overreact but be sensible. You can call, webchat or email
It can be comforting to talk with a human voice that knows how things are and makes good suggestions.
Talking of talking is there anyone in your life you can talk with , who you do not have to hold back with and will simply listen and care? It can be a big help.
I think I've said enough for the moment, there is more of course, but I'd like you views on all this - and also particularly about the kind of art you like,
I hope to hear from you again