I wasn't a LBS at the time but I have been at two weddings where there were divorced parents involved. In both cases the divorces had happened a long time ago and there was no infidelity.
At my daughter's wedding her FIL came with his partner. The partner wasn't seated at the ceremony in the "parents" seat and her MIL / FIL were I believe at different tables during the dinner.
At my youngest brother's wedding his FIL walked his daughter down the aisle but again, the FIL/MIL weren't obliged to interact with each other.
In both cases traditional "parents / bride & groom" pictures were taken. There was some tension but overall everything was fine with people focusing on what really mattered.
If my son were to be married I think that I could hold it together and be civil to my ex even if she showed up with her guy but I would certainly minimize any interactions.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells