Help!

Ashley

So I’m dating this kid and right when we started talking this girl that he slept with before me started talking a lot of shit about me basically trying to get him to cut me off. When he didn’t believe her and ignore her after. He told me that they were close friends and they would rant to eachother about his ex and her baby daddy, well i then found out they fucked. But he claimed he just didn’t mention that cause i didnt ask. So now she’s constantly snapchating him and he claims he doesn’t reply but she keeps doing it. I’m tempted to ask him to just deleted her but is that crazy of me?