So, lately I have been wondering why everytime I ask for the mail key to check it, my kids father will never give me the key & lie and say he gave it to me or says that we will check it whenever he gets off from work. Well, I waited today by the mailbox to get in and another renter let me in.... I found another person's mail with the same last name. So, I assuming he got his new phone by using my son's social security number. I asked him what he had to do to get this new phone and he stated he had to pay a previous balance and the bill of the new phone, which I had to do before with my new plan. Apparently, he used that same story to cover up his lie. My son is four years old and he doesn't deserve to have his credit ruined already. His mother is also known to use his social and apply with stuff over the internet. The apple doesn't fall too far from the tree. When he found out she did, she lied about it and he was upset it. Now, I'm trying to figure out why he is doing the same thing to his own child. Smh.

What can I do about it? I feel like leaving him and this relationship. I also do not want to let him know that I opened this mail and seen what was inside and I now know his lie.
Is there a way I can call social security and report fraud? What are my options and consequences?

Please, help!