This is an abusive relationship. It is already at the 'severe' stage. You know or suspect this or you would not have posted here. Well done for that. Let it be the first step in your journey out of this relationship. A short journey, hopefully, and one you need to start RIGHT AWAY. Don't forgive him. Don't 'let it go'. You'll be letting other incidents go in the the future if you do, and you may not survive one of them.
This is scary:
my boyfriend is a very CALM person. he would never ever raise a hand to anything and he is always under control
Often an abusive man will exhibit a dual personality. You knew him as a very calm, controlled person. Right up to the time he hit your face and tried to strangle you. YOU NEED TO LEAVE THIS MAN.
There are lots of really nice guys, very calm, such gentlemen, who are doing time in jail for injuring or killing their wives or girlfriends. I bet many of them are really sorry. And the women are scarred or worse.
he bitch slapped me once
[with object] US informal
Deliver a stinging blow to (someone), typically in order to humiliate them
and choked me for a couple of seconds.
This is very bad.
Progression of Domestic Violence
PHASE 1: Pre-battering violence: verbal abuse, hitting objects, throwing objects, breaking objects, and making threats; increased tension, anger, blaming and arguing. When abusers hit or break objects or make threats, almost 100% resort to battering.
PHASE 2: Beginning levels: pushing, grabbing, restraining.
PHASE 3: Moderate levels : slapping, pinching, kicking, pulling hair.
PHASE 4: Severe levels : hitting, choking, beating with objects, use of weapons, and rape by intimidation, threat or force.
PHASE 5: Calm Stage: Abuser may deny or rationalize the violence, apologizing or promising not to repeat the abuse.(may decrease over time)
The progression of domestic violence may alternate from tension building, where the victim is walking on eggshells to avoid abuse, to the apologetic and remorseful abuser after a violent incident has taken place
Read this page:
i was just wondering if i should ever forgive him for that, or should i let it go?
Often the victim feels they have a duty to forgive or overlook the violence, e.g. because they think that as a woman their role is to forgive, accept, smooth over things etc. If you do this you will be sending him a clear message, that he can get away with attacking you.
You should leave this relationship NOW. It may not be easy. I know a lot of people say "Why doesn't she just leave him?". It's often not that easy. You have some people on your side. Your parents know about the situation and are concerned. There is legal help you can get too.
You may well find that the prospect of the end of the relationship brings out his violent streak ("separation violence"). He may threaten you or resort to various tricks to try to win you back, e.g. promise to go to anger management classes, turn to Jesus, etc etc. You have to be strong and get all the help you can maybe including legal steps.
Again - read this page.
He did it once and he can do it again. Do you want, some time down the line, to be trapped with him, maybe with kids, getting bitch slapped and choked because you did his eggs wrong or smiled at a guy in the mall, or whatever?