Yes, it's harassment (persistent annoyance) of a deadbeat and it seems to be entirely legal and justified based on your fact recitation. Your factual statement suggest this is a collection effort against you for not meeting your legal obligation to pay as ordered by a court. Your fact pattern suggests the one breaking the law is you, sir, not the attorney and that you, not the attorney, are the one acting unprofessional and I am sure the attorney is also tired of it (your excuses), too. You're not going to get much sympathy from attorneys on Avvo for you "harrassment" claim. No, more likely you will get called a deadbeat.
L2BL: One person's persistence is often harassment to another. Depends on whose ox is getting gored.
So far, this is free to you. Until you pay a fee, I am not your lawyer and you are not my client, so you take any free advice at your sole risk. I am licensed in IL, MO, TX and am a Reg. Pat. Atty. so advice in any other jurisdiction is general advice and should be confirmed with an attorney licensed in that jurisdiction.
It is in the nature of legal disputes and especially family law disputes that there are hard feelings between the parties. Sometimes attorneys fall into that kind of alignment with their clients and it is unfortunate and the attorney often learns a hard and unpleasant lesson as a consequence. That said, in the context of litigation the standards for what constitutes harassment by opposing counsel is quite specific and nothing that you have described here would come close to that. In fact, there is very little recourse for a party who finds the opposing party's counsel rude or obnoxious and the attorney you are complaining about is not even near the edge of unacceptable conduct.
My responses to questions on Avvo are never intended as legal advice and must not be relied upon as legal advice. I give legal advice only in the course of an attorney-client relationship. Exchange of information through Avvo's Questions forum does not establish an attorney-client relationship with me. That relationship is established only by individual consultation and execution of a written agreement for legal services.