Open container and driving home

My boyfriend and I got into an argument over alcohol. He accused me of black and white thinking because I threatened to break up with him over a couple of instances. It’s my first real relationship and he is on the spectrum so trying to get more outside info on this. And I am aware I may come across as stupid for sharing but oh well. Situation 1: while driving he had a sip from a cup. I asked what was in that cup and if it was alcohol and he said yes but only a little. When I flipped out on him he said that a certain percentage is legal in your system. When j said if we got pulled over he’d be in trouble and that he would be stupid to take such a risk when he is in the process of trying to get more custody or time with his kids.
Situation 2: we were about to leave a party in 30 mins and he had a glass of wine in his hand. When he sat it down I grabbed it and was about to toss it out. He said he didn’t want to just sit with an empty glass. Later he drank it. I asked him why he lied to me and he said because he knew I would be upset if he told me he was going to finish it anyway. I told him I don’t feel comfortable wirh both situations and threatened to break up.the only way I think we could stay together is if I never ride with him before or after parties as to me this is stupid and unsafe. But part of me wonders if this is just controlling as technically ride share drivers are even allowed a certain percentage of Alcohol in their system. Opinions welcome. And no partying doesn’t happen often. Maybe once or twice a month.