When I'm around my girlfriend's children next I am thinking that I might raise my voice.
You are likely to be the cause of irreparable harm to your relationship with your girlfriend.
That's interesting. Your answer is very similar to the recommendation by the psychiatrist I asked for advice.
It's wrong to raise your voice on someone, especially your gf's kids. You will cause more harm than good.
You don't get this, it's not my fault. I don't have to follow any rules.
You don't have to follow any rules, you are right, but if you want to keep your girlfriend and be allowed near her kids then you won't raise your voice at her children. Why put your relationship at jeopardy for this?