Welcome!  The good news is that you've come here early in your journey.  There are many, many of us who have been thru it all, ranging from young, just marrieds to older veterans, like me, 77.  The nice thing about Steptalk is the diverse members, every occupation, country, situation.  I would suggest that you read here deeply.  These people will give you good, solid advice.  Again, welcome!

You will get lots of great advice here! Lots of SMs in your same position. I'm past the majority of the drama of StepHell; just ocassional blips from a group that ranges 28 - 42 years old. Like JRI, I consider myself an "older veteran" of StepHell. I'm 60. I only wish I'd found this board much earlier than I did. But I've still learned so much from the members. Take some time to read through some of the posts. Best to you!

Also a SM here with a worthless BM. My YSK (youngest stepkid) lives with us full-time and is also in therapy, partly due to their mother and her crazy. My OSS (oldest stepson) also lives with us when he is home from college and he is having to learn what kind of relationship he wants with his mother as an adult. BM sees YSK EOWE (every other weekend) provided she has a working vehicle since she decided to move an hour away.

Read around and vent away!

Steplife can be hard.. even when you have amazing skids..  The stress of finances.. watching funds go out the door in alimony or CS can be frustrating.  The kids may be in your home a significant amount of time, but your partner may not support your leading role in the home.. and may hamstring your efforts to set boundaries and expectations of people when they are living in your home.  You also have to deal with the potential spectre of the EX.. who can cause conflict and drama in a variety of ways.

Just a few things to consider and keep in mind that may help.

1.  He married the crazy.. not you.  If she is rude, combatitve or tries to start drama with you in your home.. or when you are going to pick up the kids.. or is objecting to how they are cared for in your home?  Your DH is the one responsible for dealing with her not you.  That may mean not allowing pickups at your home.  Not going to exchanges.. blocking her from social media.. not allowing her to directly communicate with you etc..

2.  Figure out how to accept and make yourself comfortable with his obligations.. financial.. custody etc.. if those things are agreed upon prior to your relationship.. and the custody order is set.  You should make every attempt to allow things to go as planned and ordered. Sure.. there may be an extreme time where he has ordered custody.. and you have some huge conflict.. and yes.. a NCP can decide to not take his custody time (can have other consequences though.. )  but generally.. making peace with his obligations helps.

3.  Understand that while you do have a say in how people behave in your home.. and your house rules.. these are NOT your kids.  They have two parents who have the obligation to care for them and support them.  Be mindful of that.. understand that parenting will come best from an actual parent (not that you can't stop a kid from jumping off the roof..lol).. You may like and care for his kids.. but it isn't a betrayal if they love their mom more.. even if she isn't a great parent.

4.  Again.. understand that these kids are not the ones that you generally should expect to be thankful for your pitching in and caring for them.  You are doing a favor for your HUSBAND.. HE is the one that owes you a debt of gratitude for helping him with his responsibility.

5.  what you do for the kids.. effort.. money.. is voluntary.. they aren't your kids.. don't be strong armed into spending your resources on his children.. do what you WANT.. and if that means separate finances while they are young.. so be it.

6.  Make sure your DH backs you up in your home.. with his ex.. with his kids.

And welcome to stepparenting.

Do you have or plan to have bio children of your own?

I have no bios (just dog cat and rabbit), and two SD- SD23  and SD16. SD23 lives full time with her crazy toxic Bm in a 1 bedroom apartment and SD16 is 50/50 week on week off. Ive got a blog spanning almost 6 years!! 

I feel the most important thing in steplife has been (for others more than myself, still working on this) having a supportive bio parent that understands you two need to be a unified team and work together staying together and strong TOGETHER.

Vent as you need to and read as much as you can stomach.

Some of us before the internet,  had no place tog go,  and really had no one to vent to.  These divorced SO never blames themselves,  Then never think that they screw up,  and had the responsibility to fix things themselves.  But the SP should total jump in and be the other parent,  even though they had little say in family life. 

i my case BF never did a thing , never pick them up or took them or support them.  That all was my problem. I nenry could take my SO out without paying for a babysitter.  What would cost more then the movie.

we were told that is life