Your boyfriend is following the typical pattern of an abusive partner. Episodes of violence, be it physical, sexual, or emotional, are followed by a period of consideration and affection. The partner may dote on you, may say sweet things, may buy you gifts; anything to look redeeming in your eyes and make you doubt the legitimacy of the abuse that happened. It's manipulation to make you stay so they can continue the cycle of abuse. You're left questioning who is the real "them" and who isn't. Your left questioning what's wrong and what's right. The whole time you are vulnerable to their attacks until the cycle is broken, whether that's by you or outside forces.

Your boyfriend choked you well beyond any "kinky" point. You did not even give consent of any form in the first place. You gave the signal to stop and he kept going. That's assault. Go to the police. Talk to a domestic violence hotline and shelter, do research, and find ways to leave safely. You're right; it's not always safest to just up and leave, contrary to what many people tell you when you tell them your partner is abusive, so you need resources to decide what steps to take in leaving him. I also wonder if, in addition to your counselors, you might talk to your parents. Parents aren't stupid. I'm sure they've suspected you're dating someone, and even if they haven't, any anger they might have will be secondary to the danger you, their daughter, are in, and to the fact that someone hurt you. They may be able to help.

Yes, it's serious, and yes, you deserve help. You also deserve to be in a healthy, supportive relationship, and I would suggest once you leave this one that maybe you take a little while to decide what that looks like for you. Generally there needs to be mutual respect, consideration for boundaries, and clear, open, and healthy communication. Fights don't need to happen, especially fights that lead to violence of some sort. You deserve better.

Good luck and PM me if you need anything else.