If she's the one initiating the dinner plans, has asked a few times, and followed up after you've been busy with friends/traveling/work, than maybe it makes sense to go.
Typically what we see here is LBSs asking WAS/WSs to do MC and to spend time together and to go on dates in an attempt to keep them close and work on things and not lose them...even though the WAS/WS is reluctant and doesn't really want to do it and even if they agree put in a half-hearted effort and make it clear they don't want to be there. That is pressure and pursuit which is not recommended here. Instead you want to give freedom and space...even more space than they want.
But...if your W is pursuing, than you also don't want to slam the door in her face.
What you need to do - and this is much easier said than done for the LBS - is to go into this dinner with ZERO expectations of any progress from W on the marital front. Keep it light. Keep it fun, and cheery, and playful. Make it seem like you're completely happy with the current direction and excited by life and make her wonder why. R2C has great advice on this side of things, here and in others' threads. Do NOT go in all serious and committed to trying to prove to her why she should stay. Now, that's also easier said than done when you're reeling and fearful of a potential D.
If you go in with expectations, and with an attitude that you're hurt by the situation, and with the goal to R talk and pressure and logic her into a "fix" of the situation than to LH's point you're likely going leave with a metaphorical kick.
Me:39 Ex-W:37 M:7 T: 9 S:6 D:3 BD/IHS/Confirm EA/PA: Feb '20 OM1 affair ends: May '20 W/OM2 & moves out: June-July '20 W files for D: Jul20 OM2 confirmed: 9/2020 Divorced: May '21
