Sorry for your lost. Please take good care of yourself! I want to suggest this book for you to read. It is a book by an anthropologist who is also a stepmother, explaining the structural difficulties for stepmothers. I think it can resolve some of the mixed feelings you might have. Hope it will help!
https://www.amazon.com/Stepmonster-Look-Real-Stepmothers-Think/dp/1517071380
I really liked the book stepmonster
Stepmonster: A New Look at Why Real Stepmothers Think, Feel, and Act the Way We Do https://www.amazon.com/dp/1517071380/ref=cm_sw_r_cp_api_glt_fabc_2SV9CX24WHT8QSH6YTGA
As others have said Disengage. Read Step Monster for help, techniques and guidance. https://www.amazon.com/Stepmonster-Look-Real-Stepmothers-Think/dp/1517071380
> "I said, the kids are your responsibility too!"
HAHA nooooo you should absolutely say "the kids are your responsibility END OF SENTENCE!" At the end of the day, they are not your responsibility at all. This is a huge issue of expectations on both your ends and is worth a really long, really in-depth discussion of the matter.
You have done what other stepparents warned me NOT to do—and I'm very glad I heeded their warnings—and that's to get very involved in childcare logistics, early in the relationship. Your husband has now assumed that all of these things you do are not only okay and acceptable for you, but expected and your sole responsibility. This expectation needs to be reset, which is NOT an easy thing to do. Once you become really involved with childcare and logistics, it's a lot harder to step back than it is to take it slowly in the first place (which is why I am so strict with my boundaries, only being in this relationship for 2 years)
So you guys need to sit down and talk. "Anything I do for the kids is voluntary, and shouldn't be an expectation. Even if I seemingly don't have anything "better to do" I'm the one who decides if I am ready/willing/able to do something for them. I did not bring these kids into this world and while I love you and love them and want to support you and support the family, I am not going to do things that are beyond my comfort level. I've been a parent for less than 4 years, you've been one for 12 years. I'm still new. You've built up an endurance for what it's like to do parental things for years, while I was thrown in all at once. I am not a full parent to them, and sometimes I need to take a step back to center myself. The logistics of transportation have become too much and I want to step back, which means you, as their parent, need to come up with different solutions with BM."
It's not an easy conversation. He might have the expectation that you will act like a full, legal parent to them, but that expectation needs to be shifted. They already have 2 parents. You are there to support him and help him, but NOT at the expense of yourself. Opting out of childcare, driving, discipline, etc does not make you a bad stepmom, or a bad partner. It makes you a stepmom who is choosing to protect her own sanity, so that she can be a better stepmom and better wife.
You aren't wrong, and you are 100% within your rights to create boundaries. I would strongly urge you to read Stepmonster, which is a key book in learning how to create boundaries and stick to them in blended family relationships. https://www.amazon.com/Stepmonster-Look-Real-Stepmothers-Think/dp/1517071380
You've got this. You deserve to be happy and I believe you can find it, if you and your partner can have some open and honest communication. Reading Stepmonster will help give you the language to empower yourself and your position of wanting to step back and not be responsible for kids who aren't yours. Best of luck!
You are welcome over in r/stepparents where we talk a lot about topics of blending families and childless folks (like I used to be) entering into a family split apart by divorce.
If you haven’t read any books, there are some really good ones out there, particularly Stepmonster: https://www.amazon.com/dp/1517071380/ref=cm_sw_r_cp_api_i_feavFbK6KE7NG and also Building Love Together in Blended Families https://www.amazon.com/dp/0802419054/ref=cm_sw_r_cp_api_i_RcavFbZ79TT5C
The biggest things are, how do you feel about kids and how much experience do you have with kids those ages? What is the coparenting relationship like between this woman and her ex? How much custody time does she have, and is there a court-ordered custody schedule that is followed? How long have they been separated before this divorce?
All these things could potentially hold big consequences. Dating someone with kids too soon after a divorce could make it really hard for them and for the ex to accept you. You not having any experience with kids could mean a huge lifestyle shock as you transition into family life. There’s too much to go into in one reddit comment, but hopefully if you have any specific questions you feel comfortable enough to ask them on the stepparents subreddit!
I came here to cautiously recommend therapy. My recommendation caused strain on our relationship. It turns out guys don't want you to send constant emails about every therapist within 20 miles who sees kids... If they go to therapy and you're privy to the info, read up on the diagnosis to see how you can help them thrive! I'd also spend less time parenting and more time reading up on step/parenting. Terrible twos often bleed into the threes. Reading was incredibly therapeutic for me.
Stepmonster - popular here, I'm a fan Single Girl's Guide - never read, well reviewed How To Talk So Kids Will Listen The Whole-Brain Child Subtle Art - best book ever