Ex husband remarried for the 4th time, 2nd new stepmom in a year?

My exhusband recently got involved with a woman with 2 kids the same age as his own. He no longer has alot to do with his own girls to busy with his new ones I guess. I caught wind they have married recently with her girls there, his girls don't know anything about it. He is coming into town this weekend with new family to tell the girls. Am I being crazy because to me this seems like a bad father not even including his own kids. Am I wrong? Don't know how to make our girls not be so sad. Any Suggestions?