splitting the bills

I don't really know what I'm here asking for. courage I think, Strength maybe... tips?

Anyways..

I grew up with a mom who put me down always, and a stepmom who would always put me behind. She even refused to cook for me because it cost her money, while her daughter and daughter's boyfriend were fed special more expensive foods.

When I met my SO 8 years ago, I kinda vowed that his 3 kids' best interests would always be my priority nr 1.

But I feel like he's been using that against me ever since.

He has persuaded me many times to buy him cars (our car technically, but I don't drive) for OUR family and taking out loans and everything, in my name.

We now have a child together.. and I notice that I am sinching in the expenses all the time. my clothes and our child's clothes are almost all second hand, as are our child's toys are usually free or birthday gifts. Even the trampoline he got for his birthday last year (our kid will be 2 soon) he sold before the summer because he and his children decided a pool would be nicer than the trampoline. While my kid and I are in hand-me-downs and rarely buy new stuff, he has max budgets to match his ex for his kids for gifts, he doesn't hold back on spending on trips, he gets them expensive shoes even though he's already paying half of what his ex is buying anyways,

I am going on 30 and I realized that I have nothing, I own nothing, I am not building anything good (credit, pension,...) While I am bringing in thesame amount of money monthly from work.

I need him to split the bills. Even if it affects my stepchildren. and that hurts me because of what I went through with my stepmom. But my SO told me.. what if I can't pay for the basics... are you just going to let me struggle? I asked him what he would have done if he would have been single. he said he would be dead if he were single (he means suicide) .. but he's been telling me this for a while and had had help, is now refusing help.. idk if he's just using it to manipulate me tbh