My ex has had an on again/off again relationship with OW. He is a serial cheater, so I think he is hoping to play the field a little and won't commit to living with or marrying the OW. At least not for a while.
Truthfully, though, I do not know what their relationship is like at all.
So to answer the original question: No, my ex has not married and is not living with the OW. My kids do not care for the OW and rarely spend time with her. I believe they think she is "ok" but just don't enjoy hanging out with her. They seem to be well adjusted, and I try to keep any bitterness or sadness I feel from affecting their relationship with their dad. He is very much a "Disney-Dad" but does keep up with his visitation and child support.