Lost

(I am speaking to my GP next week) I feel like the biggest failure of a mother, probably for a good year I've been dealing with what I thought were just really bad terrible 2 tantrums, I thought because I had smacked him or his father had smacked him it was my fault, that I had made him this way, that because I had smacked him I had taught him to be this type person, I still think that if I'm being honest, but today my dad witnessed one of "the tantrums" it was the first time anybody had seen it because he only ever did them with me, too me, he is violent, he will kick, hit, bite, scratch, scream then hole house down, doesn't have to be anything big that sets him off and it's not like it one particular thing, it's just out of the blue, not every week, sometimes twice a week there is nothing regular or consistent about them. My dad is genuinely worried for me as my son gets bigger and older, he already hurts me and he's only 3. He knows what he's doing, he remembers it, sometimes he'll come say sorry (without being asked) then sometimes he tell me he's not saying sorry, we usually talk about it after a little when he's every one has calmed down. I just don't know how I got it all so wrong and I don't know how to help him. I'm a single mum his dad takes responsibility when it suits him, I don't know if I have any real questions, it's just a bad day.