Most of the time step's relationships will be strained to varying degrees with the exs. It's uncomfortable for everyone which is only natural. Remarriage is common, but that doesn't mean it is easy. And no, it's not just a marriage do-over. My husband has a great shirt that I have to admit is my personal favorite that says "I used my mulligan on my first wife." Oh, if only it was true. If only he really could take a mulligan. If only it was that simple.
In a first marriage, it starts off as being all about the couple. Just the two of them. *sigh* Oh how I would LOVE that. Yes, we all come with baggage in some form or another. We all have a past and that past is what makes us who we are, good or bad. A lot of second marriages come with not only baggage from the past relationship itself, but also the product of that relationship in the form of living, breathing, talking, feeling little reminders... AKA stepkids.
Many a stepmom spends a good bit of their time trying to figure out what exactly their role as a stepparent should be. Are you a mom/ bonus mom? Are you a friend? Are you just "dad's wife"? Every situation is different. Different things are right for different families. Every blended family has to decide for themselves what is best for them... I wish I could give you all the answers, but I can't. No one can. There is no one-size-fits all role description... it's something that you and your significant other have to decide for yourselves in your own home. I can tell you, though, that a lot of times those first few years of trying to figure it out, especially with older steps, is like trying to nail jello to the wall. No matter what you do, it just won't stick.
Eventually, though, you and your husband will have to come up with an idea of what your role in the children's lives should be. The important thing in my opinion as a Christian woman is that the marriage should always come first and your husband should stand behind you 110% once that role is decided on. Yes, the kids are very important and perhaps they were there first, but the marriage is the relationship that needs to come first so that the children have a safe, stable home with a good role model of what a marriage should look like... because one day they will grow up and leave the nest and it will just be the two of you and they will have their own lives... and if your lives are totally devoted to the children and the marriage has always come second, the marriage will crumble because it is not standing on a firm foundation.
For me, when we got married, my role had been defined for a while and I had already been fullfilling it for nearly a year... I was to be the Mommy. There really was no "step"mother role for me here, only as mother... My husband wanted a wife and someone to love... and he wanted a mother for his son.. I wanted a family... and I got one instantly.. not only with my husband and his son, but shortly after meeting him I was pregnant with our son together and everything just kind of fell into place from there.