Please help, I might be a little insane

My husband and I cheated on each other and went through a rough patch, but now we’re doing... okayish. We’ve talked, cried and yelled our feelings out and now we’re working on a better us. The woman he talked to continues to message and try to reach out to my husband, and says a lot of things that makes it hard for me to ignore, but my husband has been ignoring it, deleting it etc. My question is, do you guys think it would be wrong of me to message her and tell her to basically cut the shit and stop trying to talk to my husband? My husband told me he doesn’t want me replying and playing into her games or whatever, but it just pisses me off and I really don’t know what to do. I told my husband how I felt and he said just leave her alone and eventually she will stop, but I feel like he wants to keep it open so he can talk to her again.