It is a challenging situation, but you don't have to become the villain of your new family. Here are some ways you can avoid becoming labeled the wicked stepmother.
Don't Try to Be Mom
You are not your stepchildren's mother nor a "bonus mom." They already have a mom and probably see you as trying to compete with her. Reassure them that you aren't trying to be their mom, but care about them and want to build a relationship with them. Let your new stepchildren call you by your first name. Don't insist they call you mom or another term of endearment.
Remember, Dad Was In Their Life First
They have had a relationship with their father for a lot longer than you have. You're the new woman in town and may threaten their time and attention from dad. Make sure they still get enough attention from their father and don't feel like you are taking him away from them. Give dad alone time with his kids so they can continue to grow their bond, without you having to be in the picture 24/7.
Have Thick Skin
A lot is happening in your stepchildren's lives right now. They will probably take some of their frustrations and anger out at you. They will say mean things to you. They will be hurtful. Don't take it personal. It is common for stepchildren to unleash their frustrations about all the changes coming their way onto stepparents. If you don't take everything they say to heart, you will have an easier time dealing with the transition.
Set Boundaries With The Ex
Talk with your new husband about setting proper boundaries with his ex wife. Make sure you aren't getting put in a position where you have to go up against mom. Don't get stuck in the middle between your stepchildren and their mom. Let your new husband handle matters with his ex wife.
Give Yourself Grace
Remind yourself regularly that this is a tricky situation you are in. There are multiple personalities, dynamics, and feelings involved. You will make mistakes through these years in handling the new stepkids, the ex wife and your husband. It doesn't make you a bad person or a horrible stepmom. Learn from the mistakes, forgive yourself and move on.
Protect Your Marriage
Make sure you and your husband are a refuge for one another during these years. Marriage counseling can be extremely beneficial to navigate this new territory. Blending families can be very tricky and it can help to have an expert walking you through the process.
Love Them
Regardless of how your stepchildren take to you, they need your love. It will also mean the world to your new spouse if you love and care for his children. Eventually things will get sorted out and they will come around to loving you too.
Creating a healthy and harmonious blended family takes time and work. With the right approach you can have a happy marriage and a positive relationship with your spouse's children.
You can read more advice from Kurt at Guy Stuff Counseling, Facebook, Google+, and Twitter.