Is it okay for someone to talk bad about you to your kids??

Well it would depend on what they were saying but I would confront them and ask them what the problem was or just ask them to stop

why does it depend on what was said?

What did they say? Big difference between Johnny stole my watch---{if Johnny did steal the watch}
and Johnny is a spoiled brat whose mom needs to spank him. One is a statement the other lies and gossip, I would confront said person and inform them your kids are OFF limits assuming what they are saying is horse hockey LOL GL MOM!

No. I dont'. Whatever is going on is between you and that person, I don't think it's fair to bring others, especially children into it too. For instance, I don't get along with my sister, but I would NEVER tell her girls anything bad about their own mother, and I hope she feels the same. It's a level of respect really.
My parents are divorced and my dad talks so much crap about my mom. He belittles her and swears at her, tells us that she's the devel. Well all that's doing is teaching disrespect to my brothers and I (I'm old enough to know better). But my brothers are going to think this is ok to talk about a woman, and their mother this way. It's not.

Telling my son I don't have my shit together, because I choose not to go to church or live my life the way she thinks I should

Do you think that is okay

Geez, sorry about the spelling errors! I know how to spell Devil...Im just a fast typer!! :D

OP no it's not okay. She has no right to bring your child into something thats between you and her.

Nope tell her to mind her own beeswax and the next time she tells your son something like that will be the last interaction she has with him--good luck!

Nope. It's never ok to involve children in adult conflicts.

OP- So how do you handle it when they do