He brings flowers to the big reveal and everything.

OP must be trying to taste the waters for writing.

I make pretty calm comments on this site but I think this is fucking ridiculous. If I were him, I would lose all contact with you and try and isolate myself away from you and Tom. Any kind of emotional put downs like that, especially in terms of love will really make him upset. I certainly don't think he'll accept an apology from you. Hell, I don't know if he wants to talk to you at all.
However, there is a bright side to this. Learn from your mistakes, and make sure to never emotionally abuse someone like that again. It may not seem like a big deal to you, but to the victim it means a lot, and it hurts.

Ouch this is pretty brutal if true. I honestly don't understand how you thought this wouldn't hurt his feelings and break his trust towards you. There's a chance he may forgive you, but thats not without some emotional scares and/or lack of trust towards you.

I'd say let the guy cool off for some time, try to apologize, try to make amends, but don't try to force it.
Maybe Promise to not do any more pranks on him(?).

first: you have my respect for posting this story, what you did takes some courage to do and is better than to simply ignore what you did.
second: I don't really have a advice that could help you, but I would at least give him some time alone (a week or so)--means no visits, no messages to him and don't apologize to him over and over again, give him time to overcome this and then try to make contact with him.
If he makes contact to you first then go for it and in the end ask him what you can do to make up for it if you have a good or great bond nothing to worry about, (if not then you have to look for another person for you to tease.)

but in the end you deserve every bit of insult for you, you see in this thread.

((Edit: if this is a joke I would laugh at you for making a wall of text just for a "nanananana that was a joke lol"))

Well, you should definitely change how you act towards others. You also should make sure that he is all right and that he is not going to harm himself. If Tom is bad influence on you, avoid him.

Kissing prank.... Gone sexual!

Seriously though you really need to start being nice to him. As cousins And friends get older they move on and stop seeing you. You should be as nice and cool to him as you can now because I guarantee if you're not it will have a negative effect on him.

Honestly, you and your other cousin sound like total dicks. Bullys. Especially, since you don't make it sound like you even like the guy particularily, so you're just picking on an easy victim.
It might be a diffrent thing if you all had been equal friends for years, and even then it would have been a dirty prank.

As it stands he's totally justified in not forgiving you. If you're honestly interested in keeping a good relationship with him, or anyone for that matter, you should reconsider why you feel the need to hurt others in order to elevate yourself.

And if this is a joke thread, congrats, you got a reaction.

Sorry, but that's a dick move. I'm a calm guy, but I probably would have attacked you without thinking rationally.

The fact that he is alone most of the time makes it worse. Imagine how hard it will be for him to find anyone ever again? He'll probably keep thinking that anyone who "likes him" is probably another sick joke.

Not cool though. You better make it up. Big time.

What a dick. Why do you want him to forgive you, so you can still make fun of the poor guy?