Concerned about my son's behavior

I am divorced from my ex-husband and father of my two children, 9 and 6-year-old.We divorced because he was abusive - he manipulated me and the final straw was him being aggressive and hitting me and choking me in front of the children. He got worse over the years and it is still a huge struggle for me since my children still have to visit him twice a month for the weekend. He is also abusive towards them. There is nothing I can do to help them because the country I live in sees slapping as normal and all his others aggressions (like not giving medicine when sick, forbidding them to play in tournaments of their hobbies when it's his weekend, consistent shouting, not feeding them properly, taking away money I give them to spend on themselves, ignoring their feelings, making them study and just being mean) are apparently acceptable ways of raising children.This is very frustrating for them and obviously for me. The kids went to a psychologist for a long time, but before the summer they were in a good place so it was decided that we should pause it. Again mental health awareness isn't really a thing here.I have been with a new partner for quite a while now and am currently expecting a new baby.My children call my partner dad. They absolutely love him and adore him and he loves them back. They asked to call him dad about a year ago. He drives them around to their hobbies, introduced new hobbies to them, tucks them in and listens to them. He is very calm and has given so much to our family. He even supports the kids financially... His family is very big and all of them have taken on loving the kids as their own family. His brothers visit the kids and spend time with them. Build things. They also have my parents and sisters who love them so much. They both have great male role models aside from their own father. Communicating is very important in our household and they both know I have zero tolerance towards violence.My older son,9, has always been sweet and quiet. This summer was very difficult for him with his father and since then there have been a few misunderstandings between them. My son hates his biological father, but there is nothing I can do to help him. I know he is frustrated and angry. His biological father with all his terrible faults, still loves his children and wants to spend time with them and sometimes he does amazing things with them, but still, my son comes back confused and unsure how to process this.This last month my son has been aggressive towards other kids 3 times! The first time was on a hockey tournament. His team was losing and he attacked a few? I wasn't there. He told me and we talked about it. His (step)dad talked to him about it. We weren't angry. He wasn't punished. We just agreed that he was frustrated and tried explaining to him how else he could handle it.The second time was yesterday. Our community here does trick or treating. For the first time, he was allowed to go alone with his friends. He came home happy and was getting ready for bed when his friend's mom called and told my son had been beaten down by an older kid. We immediately asked him what happened and he didn't want to tell me, only his stepdad. So he admitted to his stepdad that the older boy was walking to close to him and then my son attacked him. The older boy was stronger so my son said stop. The kid was stopped and they both went on their separate ways. My partner talked to him about it, but again no punishment just talking about how to handle yourself.Now today for lunch my daughter comes home and tells me her brother kicked her off the swing and she fell. He comes homes home shortly after that says nothing but can't look me in the eye. Now I was very upset and told him that this was strike three and that he has no right to game, watch tv and has to give me his Halloween candy until further notice. I was upset and maybe a bit loud and harsh in my tone so he stood up and slammed the door to his room.My partner says that when he was his age he would often be aggressive too without much of a reason. I know boys are a bit wild and will get into trouble, but is this still normal? Should I call his psychologist? I'm so afraid of him turning into his biological father and my ex-husbands biggest issue until this day is his enabling parents who never make him stand up for his actions and always find a way to excuse it and help him out.I don't want to blow things out of proportions - I just want to help my son. He is so loving and intelligent and a really great kid, I don't want him to lose that. Should I worry? What can I do to help him?​​​ via /r/Parenting https://ift.tt/2SBWxrZ