When in doubt, err on the side of being less available and responsive. If he's texting you something flirty, he's trying to confirm you're still there and interested. I'd hold off on responding. If you have to respond, give it a few hours (because you're so busy and important ) and then answer. You can be kind and interested like you would be to a neighbor but not like his wife, especially if this is how you guys have interacted in the past. Always end the conversation first if you do get dragged in.
Also... I just took a look at the infidelity section in DR and am a bit confused about what you're talking about. The section in infidelity when your S won't stop seeing his AP or other people more generally and is still saying he wants a D... I don't see anything in there about giving your H when he's getting from the OW. That comes later when you're healing. The closest I see is when she says drop all pursuit and all talking about the A and act as perky and upbeat as possible when he is around.
I think as Steve says, the key is that some of the advice is hierarchical. Stopping all pursuit behaviors is a primary one. If flirting or connecting with him has any flavor at all of pursuit, don't do it. You'll be working against yourself. Yes, act breezy and confident and totally fine when you do see him. If he initiates a conversation, validate and listen and end the convo first and go on your merry way. You'll start to see the effects of backing off and when you do... DO NOT STOP.
keep up the good work!
May
Me (46) H (42) M:14 T:18, D9 & D11 4/19 - 12/19: series of escalating BDs 9/20 - present: R and piecing
) and then answer. You can be kind and interested like you would be to a neighbor but not like his wife, especially if this is how you guys have interacted in the past. Always end the conversation first if you do get dragged in.