In dire need of some help I just need a couple of minutes of your time...please

I've been struggling with weight loss my whole life. I'm 19 years old 5'11 and weigh 280lbs. I can't remember when the last time I was thin (probably when I was 5 years old which is pretty sad) and from there on out I was the fattest guy in the room. I will join a gym in the next couple of days but the thing is that, I have no problems with doing exercise but the problem lies behind my diet.

I really haven't read anything similar to my unhealthy way of eating when I read this subreddit but basically I just eat 1 meal a day but its the grand poobah of all meals. I eat at around 9pm ( I go to sleep at 3am or so) and that meal is almost always junk food. For example I'll eat a large whopper meal with an extra whopper sandwich and one apple pie, but that's the only thing i'll eat during the whole day, barley any water, no snacks and no breakfast or lunch.

I've been hearing about keto so much and would like to give it a shot but I can't eat anything with pork yes this includes bacon (blasphemy I know) and the only type of eggs I eat are omelette's. any thing else if fair game.

So please reddit help me How should I eat? What should I eat? And what type of exercises should I do?

ps: I live in a country where its easily over 125 degrees during the whole summer. Just throwing that out there if it has anything to do with how much water I should drink.

pps: Sorry about my English I'm not a native speaker.