OP, I'm in an open relationship. DP and I got together (after a year of friendship) both knowing that this was what we both wanted. We talked (and still talk) about it a lot, and when new situations arise we check in with each other about how we feel.
There have been times when something that one of us has previously been okay with, has changed, and one of us has felt weird or unsure about something. At that point we talk to each other, work it out, adjust our boundaries if necessary, and move forward.
It's working so far because we respect each other and feel secure talking about our insecurities without fear of being dismissed or ridiculed.
A good open relationship can be brilliant, just like a good monogamous one. But only if it's what you want.
You are not in an open relationship. You're in an abusive relationship with a disrespectful selfish bastard who is walking all over you and getting annoyed because you're not happy about it. I've been there. Leaving is hard, but oh my gods, the relief when you finally break away is just amazing.
The two best things I ever did were to leave my ex (It was hard. I was pregnant and had another DC as well) and then remain single for several years afterwards. Now I have the strength to find and maintain relationships that work for me and the people I'm with. Your partner is only interested in what works for him.
I don't know you. I don't know anything about your background, how you live your life, or what you think you do or don't deserve from relationships. But I absolutely know that you deserve way way better than what you're currently getting.