Could my in law be jealous?

I've noticed she's just very bipolar one second she's my friend next second she's against me treating my husband like it's only hers such as

-cooking for him when I do too and she asks him "do you like it?"

-does ONLY his laundry

-asks him if he likes how she's dressed

-drinks in the same cup or bottle as him

One time we had sex and afterwards I asked her if my baby fell asleep since she was over to spend time with him and she completely ignored me didn't bother to answer my question... she probably heard us lol but still... what's her problem???