Alimony nonpayment

My exhusband stopped paying my alimony. I sent his atty a certified letter demanding unpaid alimony and mediation as the contract called for. There are other severe Breach of contract issues as well that do not call for mediation. The certified letter was not delivered as no one was at the firm, a notice was left on the door, and the item is at the post office for the last 10 days and they are not picking it up. Can I consider this my notice sent and a refusal to mediate, and go ahead with filing my complaint? His attorney knows it is from me and she is ignoring my response.

or can I send my ex the letter in the mail and skip the game playing atty. Which would be better?

You can mail it directly to your ex instead.

Do I have to send him something? or can I just file because I tried to send it to his atty and she did not pick it up at the post office after I tried to have it delivered to her. I gave them 10 days to respond and the 10 days is now up…

You should send it to your ex.