[Eternal]

He cheated on me about 8 months ago with my best friend.

He fell to his knees and grabbed my legs and cried, telling me he had cancer and that his dad beat him until I felt so bad I told him we could make things work again. I am convinced by now that he does not have cancer at all.

Now he hurls a bunch of spiteful, hurtful words at me and each time, he raises his voice more than before.

Then he says that even though it is my fault because I hurt him, he will make a change.

This was all just in the first half of your post. Your boyfriend has been lying to you about pretty major things such as cancer, won't admit when he does anything wrong, and is very manipulative. These are all red flags of an abusive relationship, and I agree that you need to leave. Why would you want to stay with someone who puts you down and almost hits you when you can find someone who will treat you with respect? And I think you know that, this whole post was pointing out his flaws and the bad parts of your relationship. I did not see much good things said about him at all. This behavior is definitely not normal, and it seems you may have been with him for a long time but that doesn't mean you have to stay. I highly recommend leaving and blocking him on all forms of social media. After all, you talked to his ex and he did all the exact same things to her and she finally left. You really should do the same and get your friends and hobbies back so you can be your own person again, and I promise you'll feel a lot better.
You should check out loveisrespect, it has a lot of good information about abusive relationships and some helpful resources.