Any advice?

I’m a stay at home mom. I have an almost 3 yr old who’s autistic. He needs to be taken to the school and therapy. He’s nonverbal so I stick by his side as of now. Recently my son’s dad did his taxes and just got a large amount of money back. He doesn’t plan to give me any money either. I basically live off my sons SSI which isn’t much and my sons dad uses SSI against me. Saying I have that money. However that money is equivalent to 1 of his paychecks per month. I feel like I deserve something. He got the child tax credit and all the perks. Meanwhile I’m broke. Need new shorts and my car needs to be fixed. There’s things I need that I cannot purchase with SSI money. This guy is using me for my son’s SSI money while he lives his best life. Honestly is this even normal? I’m starting to feel a bit resentful about it. His money has nothing to do with us. He gets mad if I don’t spend half on the grocery bill but I’m broke man. He’s trying to make me more broke. Idk am I overreacting? Yeah we’re not married so technically he doesn’t have to share anything with me. I want to get my perks of being a stay at home mom who works her ass off. I’m not seen or appreciated at all and it’s really exhausting. Any advice? Update: he doesn’t pay child support we live together as of this point in time.