when my kids come back from visiting their father, his "new" wife likes to send pictures back of her with their dad or all of them together and it's really upsetting to me. Am I wrong for being so upset about her sending pictures of herself with them?

I think I would be upset if it were me in my situation. Why is she doing this? Maybe to let you know their dad IS spending time with the kids, and that you dont have to worry about them? Showing that she is trying to be a good step parent? Or is she trying to rub in your face that they have a good time together. I dont know her, or the situation. What do you think she is doing it for?

she's doing to always have the upper hand. Be in control is her thing. I have a new man in my life now and I would never send them with a picture of him with the kids

Is she sending these to you specifically, or are these for the kids? I guess I just don't see much of an issue if they are for the kids and not being sent to you. I'm not saying you should be tickled pink, but would try not to get upset if they are just the kid's for their photo albums or whatever.