Lea, back to the step mom thing. After my parents divorced, my mom had a live-in boyfriend the first summer. She was married again within two years. When that ended she got engaged to another guy (I kind of helped scuttle that one), then she had a live-in boyfriend for about eight years before dumping him and marrying an online computer repairman about six months before she died.
I liked her second husband and the long-time live in boyfriend. But at no point did I consider any of them "dad." I had a dad. These were just guys around in my life.
Your Ex can say "we" all he wants. Your kids will always only have one mom. The OW will just be another person in their lives.
Me: 47, Ds 17-13, D final 6-11 http://tinyurl.com/yk4e2tz http://tiny.cc/thread2 http://tinyurl.com/ydtphqu http://tinyurl.com/thread4 http://tinyurl.com/3sm78k6 http://tinyurl.com/thread6