Oh dear, Ilikemangoes123, your goodwill is not all gone sour. You can keep going if you can hit the reset button and wipe out all your fed up-ness caused by these insensitive teens. You've done ten years already. The next ten WILL be easier and worth striving for.
You've vented your frustration here. At home, you're not listened to.
You have been VERY accomodating.
It is now TIME
Something has to give.
So, for your sanity : Detach. DETACH DETACH !
The teens want Dad...so he and they can work things out between them. Cooking. Days out. Laundry. Etc.
DON'T WORRY ABOUT IMPLIED JUDGEMENT FROM EX. NOR HERRUMPF FROM THE TEENS. Now you need to alter things to suit you.
Now you've sent an email to hubby, and his reaction was no - action, tell him you will have to tweak things a bit at weekends just so you can shake off feeling unloved. Because you are loved. It's just all gone a bit disfunctional.
Divorce costs thousands and thousands. Avoid divorce, it's so sad and painful and regrettable. Try to fix home life.
My advice is, if you or hubby have any spare cash, get hold of it for building a runaway fund, which you don't intend using but makes you feel supported in terms of having a back up choice.
Then, also...Throw money at having a part time, independent life style from the DSC and their DF. Coffee shop visits with your two. Family trips. Revisit the family that the DSC sulked over going to. Make Christmas plans or half term plans.
Get some furniture and pictures up in the home. You can choose new bits inexpensively (thinking ebay). A Mum's chair? Things which you like (As stepmum, I like Candles...and so we have candles. To start with I didn't do this type of thing because their previous house didn't have them. Ditto there aren't photos of my family, but I'm putting that right. The step children buy me candles nowadays)
Perhaps the hubby's children would respect you more if you were more determined, less self depricating, and so try 'being true to yourself' and forcing your views more. Being soft and kind, it seems...well, they have walked all over you. Teenagers will do this (even your own) but you are allowed to be empowered as teens decision taker, the adult. It's your home.
I get what you mean, funding his children on trips their D F doesn't organise. I do that too and the DSC don't know it comes out of money I have to play around with, and how I loathe to waste it on unappreciated gifts. You have learned a lesson. Don't fund things that are unappreciated just because in the round, it is good for them. You and their DF aren't a team on this aspect, so the DF can invest in the slog of do gooding. Only give in areas you are super positive about giving willingly. And because you are a good step.mum, this will sometimes be benevolent giving, without expectation of anything in return. I gave stockings to my DSC at Christmas, as always. They know I bought them but pretended I didn't. This year they opened them at same time, same room, but separately, to my DC, and huddled together and didn't share the experience with us. I was hurt, but shrug it off as it was their need. They needed each other and needed to exclude me, steps, and actually DF. I have moved on. I gave willingly. Next year I won't buy for the young adults because they don't need stockings and it wasn't a joyous addition to Christmas. I learned. Their Dad can do them if he wants to.
Crucially, for you, giving must now be on your terms, when you are willing. And you must be more selfish and you might luckily gain some respect. It's not as scary as you think, and things can get better.
By the way, do you own half the home?