I'll make this as condensed as possible.

Husband's ex jumps from guy to guy. Left him for a work colleague, pretty sure there was at least 2 affairs (confirmed) during the marraige.  I've been with DH for 7 years, I have no kids, aged 31 and he has/ had 2 sons that we share week on/ week off care of with BM. DH is 40. 
 

One kid is now 18, moved permanently to BM's house at age 16 because we did not allow him to work shifts at McDonald's at 11pm on a school night. He became a non- binary 'he/ she' - I swear it's only for attention which actually is a slap in the face to those who really are non-binary. He was a narcissistic, self- centred, money hungry, wise guy who cared for nobody but himself. He never spend a dime of his allowance or job money towards gifts for his dad. Just expected me to pay for it all and say it's from 'us'. Just loved the sound of his own voice and was the most attention seeking prick I ever met. Just like his BM really.

Anyway, Now said 13 y.o (who is very clearly influenced by BM and older sibling, probably bacause they heard from SS that DH and I are planning to have a baby) SS comes here full of attitude on a Monday, refuses to listen to me or his father most of the time. I get doors slammed in my face for asking him politely to mow the lawns (we pay him $30 for it). When I speak to him about anything he gives me eye rolls, refuses to look at me, stared at his phone or continues eating as if I don't exist. It will not surprise me, if this is all BM, just after getting engaged she threw a huge tantrum about something kids related. Same thing just before our marraige. She never spends any money on them unless she absolutely has to and I think it sickens her that the ex has done so well to get a younger wife, a house, a 4x4 and a boat while she can't get current BF to propose or commit in anyway.

my biggest problem is, my DH does not parent. I don't think he knows how and it's starting to make us resent each other. He keeps says 'final warning' but does nothing and the kid walks all over him. When I am fed up and loose it, I remove the kids wifi (I pay for it after all) and throw his R18 PlayStation games awaywhich makes DH upset. I don't know what to do anymore. I can't live in a pigsty cause SS won't clean up after himself, nor will I tolerate rude behaviour in my own home where I pay the bills 50/50. After all out of BM and DH I was the one who paid and bought most of his needs and also planned his parties, arranged the gifts for all occassions and planned and paid 50% for him to have holidays with us. He was absolutely spoiled by me and now I'm fed up with his behaviour!! BM hasn't taken them on holiday once but is able to afford to take boyfiends always.  SS doesn't seem to see all the ways I put him first and sacrifice for him but instead, just breaks me down.

DH is upset that I said I no longer want anything to do with SS and if he can't step up to the plate and discipline his kid, that I will request kids removal to mums house and for him to only visit every alternate weekend.  I'm done being the unpaid taxi driver, cleaner, cook, carer,  scheduler etc. It's going to drastically change our family financial but a line has to be drawn in the sand. It's taken a HUGE toll on my marraige