what can be done if being stalked and harassed? can i sue for mental anguish?

my husband had an affair, the woman claims to have cancer and pregnant . My husband ended the affair , has had no contact, awaitng dna results, we have a mutual friend with her , the friend shows up at our sons game to take pictures, he gave her my phone number, and she keeps calling me making threats, she shows up to where i volunteer looking for me, not my husband, she uses calling cards to call me, the associate has no reason to be at our childs games and taking pictures