I keep losing my temper

My son is 8 and has really been testing my patience lately. He whines and pouts and complains about absolutely everything. He honestly acts like a spoilt brat (totally my fault too) but for 4 days in a row this week he has pushed me so far to where I’ve completely lost my temper. Obviously I would never be mean to him but I have raised my voice and I’ve just felt so angry that I want to smash things. I can feel my blood pressure rise and my chest tighten and it sucks, it’s a horrible feeling and then I feel like breaking down and crying . I hate this feeling and I hate that my child keeps doing this too me. I’ve had talks with him about how he can’t have everything he asks for and he can’t always have his way, I tell him that when I was a child I never got anything I asked for and rarely got my away and he should feel lucky that I’m not mean to him like my mom was to me.

I don’t know what else to do about his behaviour but I need it to stop ASAP