Hello everyone

I really don't know if this is the right place for my post, apologies if not.
It's about my 12 year old son Ryan, he is 13 in 3 weeks. I'm a little concerned about his behaviour. If nothing goes his way he goes into fits of anger and rage. He punches things, kicks things and shouts and screams.
Other times he gets very upset...but hysterically so.
The other day he realised he had lost his phone. It was a really nice expensive one and he was gutted. But I was shocked about the way he reacted to it. He cried for hours and then started saying how useless and pathetic he was because he couldn't look after it. He kept saying how pathetic he was because everything he has he breaks or losses. Then he brought up Edward our rabbit. Edward died around 4 years ago through old age, but he started blaming himself for not feeding him. This was clearing not true, but I was amazed that he brought this up and was blaming himself. Hearing my son say these things about himself was not only upsetting but quite shocking too. I finally managed to calm him and the phone or the rabbit hasn't been mentioned since.
I understand that kids have tantrums and don't like it when things don't go their way. I have a 6 year old that has plenty of tantrums.
The thing is with Ryan is that he is very creative, he is clever and he has a very sweet and loving side to him. He gets very angry when anyone hurts or upsets myself or his brother. But then I see this horrible side to him that quite frankly scares me. When he is in one of his rages he is scary, he says horrible things and basically trashes the house. When is is having one of his emotional, upset episodes he is very hard to convince that what he is saying isn't true, and it's very hard to calm him and stop his tears.
I will give you all some background. When he was born I suffered with post natal depression that was never treated. It led to myself drinking a lot and becoming very ill with depression, which in turn led to panic and anxiety. So to my dismay and guilt Ryan didn't have a very good early start. He was basically left to his own devices up until he was 3 years old.
When he was 3 I set the house on fire by accident due to alcohol. This was the wake-up call I needed. I got off the booze and starting building a good relationship between us and a nice home environment.
Ryan started soiling and wetting his pants. He started school doing this and it was horrible for him. He stopped soiling half way through primary school and stopped wetting towards the end. He still wets the bed.
I blame myself a lot for the way his is because of my past. We do have a great relationship now but he has also had to put up with me with my illnesses and the times I have been in hospital, also my sexuality.
I feel really bad for him, I love him so much but just don't want him to have the life I have had or to grow up hating himself. Can anyone relate or throw some idea's in? I'm really worried about him.

Kez xxx