She must be seeing a lawyer...what now?

[Awoken]

Here's my current question: This week WAW decided to cancel on thanksgiving with us, and went to Seattle to be with her family for thanksgiving. Her sister just had a baby. We've known the due date for a long time, so this was really about her getting away. She left me home with the kids thankfully.

Before this, we had agreed that on Dec 27th, when D17 goes on a school trip, that W would go to Seattle, leaving S13 with me for the next week including New Years.

I found out on Thanksgiving morning that for the past week, W has been asking S13 to decide if he would like to stay with me or go to Seattle with her for that week. S13 has been talking with D17 and is a little bothered with the idea of choosing between me and mom. S13 had just got of the phone and asked me what I thought of the "Seattle situation", which I knew nothing about. I told him that I he shouldn't worry about me and that I loved him no matter what he did. I didn't know what else to say. He then wanted to know why I didn't just come to Seattle with him, and I had to tell him that mom did'nt want me to come. D17 then came in and told me that he had been upset for a while about this, and I quickly said we should'nt really be talking about this, that I needed to talk directly with mom about it.

Here are my choices:
1) Tell my W to go ahead and take S13, since I just had him for a week. Sucks for me, no family or friends in town that week and I'll have to stay and watch the pets. Will likely take the most pressure off of S13.

2) Tell my W that I want her to stick to our original agreement. I wonder if she will just do it anyway.

3) Continue with VERY limited conversation with W, and let her make the choice. I don't think I can really stop her anyway.

I want to do what's best for S13, but I don't want to continue being a doormat for W. that' what this feels like.
My head is still in a fog, so I thought I would post these thoughts here BEFORE I do anything, and see what yall have to say.