Does he get physical with you outside the realm of self-defence?

while your father may be set off badly at times. I see that you're looking at how you speak your mind sometimes when you shouldn't. leaving aside all of the tangents that this thread has gone down making the issue about everyone else, I'm glad that you see that you behave in this way sometimes. This is the thing you need to address.

it's not easy to think about what you're going to say before you say it but in many if not most cases it's the best way to deal with things. I think that you know that how you blurt things out without thinking it causes a lot of arguments. Do you have a T to bring this up with?

I won't say anything along the lines of it's your stepdad's house and you need to respect him and all of that stuff... nor will I blame your stepdad entirely on the arguments that seem to be happening but I will say that you both have issues that need to be addressed here. And you can only control what you do... so with that in mind find a therapist or talk to the one you have to learn mindfulness or what ever means that would help you stop being so impulsive and at that point you've done your part in helping calm the situation.