I think it's very important to get your son out of those moments, when your WW is acting like she did on Sunday. You should relocate your keys in a spot she can't find. You son should not be subjected to her antics. And if she made declarations in front of your son, about you and him not going to church to benefit her standing in the community, think about what type of message has been communicated to him about church and his parents.
She is way out of control. Stop communicating with her, if she's in the room and won't leave, shrug your shoulders and go your way. (Don't literally shrug your shoulders), but don't give her the benefit of getting a reaction out of you. Stop reacting to her pettiness and childlessness.
Keep up the hard work.
M:36 W:36 T:11 M:10 S16, S12, S9, S4 BD:06/28/17 OM confirmed 07/20/17 Recon the M 10/29/17 Working hard:2gether
Onward and forward
This process is not a sprint it's a marathon! Patience, Patience, Patience.