I just want her out of my life

Why can’t I get away from her? I have two sons (aged 8) with my BD. We have joint custody. When our sons have homework or projects, they seem to always mention their dad’s wife. It just rubs me the wrong way. For example they had a math problem where they had to write out a word problem. They included me with a certain number of balls and added her with a certain number of balls and their dad with a certain number of balls and added it all together. They include her in pictures that they draw in school etc. Just every time I turn around I feel like this woman is everywhere in my life and I can’t get rid of her.

I know they don’t understand the circumstances but essentially this woman came between me and their dad. It all happened when I was pregnant with them so as far as they know this person has been with their dad all their lives. I have had a hard time with it and feel like I’ve been forced to deal with a woman I hate for all these years. Fundamentally it seems like people shouldn’t have to deal with people being in their lives they don’t like or want.