Legal Question in Family Law in Pennsylvania

I do not practice in Pennsylvania so I cannot give you legal advice. However, some practical advice for people in my state is this:

Get this book for your daughter: The Boys and Girls Book About Divorce, by Dr. Richard Gardner. The book's format is children's questions and Dr. R's answers. He was a counselor for children mid- and post-divorce; he compiled the children's most often asked questions. My own children thought it was very informative.

It's also a good book for parents to read. It will give you a peek into the child's point of view and what the child worries about without wanting to 'bother' you.

The text messages are a nuisance - these can be ignored. He evidently is immature and would not be doing these things if it did not bother you.

If ignoring this does not work, talk to a divorce attorney to see whether a "Protection From Abuse Order" (PFA) is feasible. It does not sound like this rises to the level of criminal harassment. If you do not meet the grounds for a PFA, you can bring a civil suit. Or you can seek to modify the custody order by having another party pick up the children and have him and his girlfirend refrain from denigrating you in front of the children.