I hate being a step mom

I think I hate being a step mom

Me and my partner have been together 3 years I have a daughter 7 he’s got a son 8 together we have a son 6 months, we met 6 years ago through my friend ( his sister ) our kids where friends from the start all was great all is great we are perfect together as a couple and parent well with our son and my daughter, everything is perfect until for 3 days every week his son comes when life becomes hell. His son is out of control he has always been very rude ( we have tired everything to teach him right from wrong his mom says he’s just like her it’s there personality) the last few months he’s became violent throwing tables, pouncing people when driving , fighting young children in the park, threatening to throw himself out windows then tell people we done it, bullying my daughter but also all children he’s around he’s now banned his aunties house due to him being so aggressive to other children ( his cousin) I’m screaming out for help and his mom tells us he’s the same with her but that it’s just boys being boys. I’m really starting to hate my life I feel so bad for my son and daughter but also my partner as he’s an amazing father and just wants his son to be happy. Iv no friends to turn to really as they all told me years ago that my step son was evil and I cut them off telling them I thought he just needed love and stability as he has none with his mom but now I’m really starting to see how bad things are and heard a woman came in to my work asked if I was in when told I wasn’t she told my boss ‘ good because I can’t stand that woman any woman that can rise a child so badly should be ashamed to show her face that child will grow up to be a statistic creepy man’ like strangers judge me on my step son . what do I do ??? We have been taken him to doctors after doctors getting him into every bit of therapy we can find nothing is working and I’m genuinely getting depressed and drained from it all please help me? Is there help out there or do I just have to wait until my step son grows up and gets into trouble with the law