Hi Scrant, I don't think 'accept some invites etc' really applies in your situation. I think you are in LRT territory as you have S and your W is living with OM.
Have a look that that section again and follow the advice there. Ask yourself - if I was really enjoying my new single life, how would I be interacting with my W? To me, that looks like not even noticing you have a text for a few hours and replying briefly but pleasantly if it is a business thing. Aim for brief, pleasant and a little distant - rather than curt. But I wouldn't respond to 'non-essential' texting as I do think your W is trying to cake eat and I think you've enabled that with the kissing and hugging (don't intend any offense here....just saying..)
So, have a good look at what LRT entails and apply that to the letter. I think GB posted a helpful link to LRT in a post to Jpeg recently...
Take care
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus