Start by being mindful/aware of the “feedback loop” that causes your behavior. Something he does triggers your responses and before you know it you’re doing it again. So, you have to slow that process down by paying attention to that exchange.
You might be acting out of feelings of threat to your security. These feelings, while real, may not be justified (because there isn’t an actual threat to your security). So possibly you need help relearning what is and isn’t a threat by getting regular feedback from someone who knows how to respond “like a normal person.”
It might work for you to set up an agreement with your SO that if you lose it, so to speak, over something unjustified, he has the right to leave the situation until you regain your senses. By him exiting the situation, the drama loop is short circuited. After you’ve cooled down, you can approach him with your “real” concern (which might, for example, be about sharing an underlying issue or insecurity that is bothering you) or just apologizing for your reaction and/or thanking him for being patient with you while you work on fixing that behavior.
By the way, I don’t mean for this to all sound as if you’re to blame for everything and apologizing for everything. I’m just going from the assumptions above.
When I personally deal with people who create drama, I really try not to reward the behavior. So I won’t necessarily fault the person, but I will give them an implicit choice between having my attention and having their drama. If they’re more interested in drama than my attention, then I stop interacting with them, and hope that they’ll figure it out someday.