I agree with Mighty Teach
"Don't let her steal your joy"
Coteaching either works or it doesn't depending on the people involved. It can either be hell or heaven. I've had both with teachers and paras.
She is doing inclusion with you for the sped students.
I also think other things are going on with her besides the classroom.
She didn't get along with the second grade teacher and now is having problems working with you
Don't change grade levels if you are happy in 1st.
Spring break is coming, summer is coming and I doubt you will be working with her next year
It's not you and you've got this !!!