You have the right to be angry with the things you have mentioned.

I know he's a great person because I remember being really happy with him at one point.

When you first meet and get to know someone, they'll show you all their good points. They'll be there very best. Truly the only way to know their true colors is how they act and behave during their worst times. You've been together only 6 months, which might seem like a good amount of time, but really it isn't.

That week I found out he had been lying to me about one of his exes.

So he lies, breaks up with you and treats you like garbage and you're worried you'll regret leaving him?

I think you need to stop living in the past where you saw his good traits and look at the big picture.

He threw away our relationship on a single fight.

This is not okay. If he was truly committed to being with you, he wouldn't breakup with you at the first instance of an issue. You work it out, you give it your all to figure it out for the long haul.

I'm sorry but I really think you are in a toxic relationship with someone that doesn't deserve you.

We have so many plans for the future, and I'd hate to let that go.

Is it going to be much of a future if you don't have a good relationship and you're unhappy?

1. He's broken your trust.
2. He's been degrading to you in regards to making a comment about how you should be a hooker because you like sex so much.
3. He's snapping at you for stupid, little things. I don't know how much and often this happens, or if its a recent development but frankly he's either got some issue/thing that is stressing him and he's taking it out on you or he's just like this in general. Either way, it's not acceptable behaviour and if he cannot admit and accept he is wrong in acting that way, that's a HUGE red flag (no good).
4. He broke up with you over a minor issue. Avoiding conflict and willing to leave you instantly, no questions asked.
5. You feel like he thinks you're a gold digger. You don't have to prove you aren't a gold digger to him. You aren't. You shouldn't have to put yourself in a bad position just because you need to 'prove yourself'.
6. His mother dislikes you already due to your immigrant status. Are you legally entitled to live in the country as a resident?
7. You slept with him and you said you regret it after all that. If this is the case, then why would you want to stay with someone you regret sharing an intimate moment with? Sometimes people have bad first sex experiences, and that's okay, it happens. It's nothing to feel badly about, stuff happens. I think the take-away from this is that you shared an intimate moment with him that you later enjoyed. You deserve better than that. You should feel happy with your boyfriend, not mad all the time and upset with him.

If you do decide to break up with him, I think you need to stay strong. Why are you scared? Are you merely scared because you feel you might be making a mistake? I think that based on a lot of things you have said, there is more bad than good in this relationship.

Maybe this is an isolated incident, but I'm not sure what to tell you because you know him more than anyone on the internet.

but I can't break up with him because I'm scared

You can break up with him. You cannot let fear stop you from making a decision that is good for you in the long-run. Think about yourself, your future and whether or not you want to be in a relationship with someone like this guy. You deserve to be happy and in a positive relationship, not with someone who would dump you over a simple fight at the drop of a dime.