I have to agree with Jessika...

Sure, he could be a weirdo. But, I wouldn't base that on anything his ex says. She is, after all, spying on him and logging onto his accounts - that is more than a little bit weird! Maybe she is trying to help you, or, maybe she's in denial about their relationship and wants to scare you off.

This reminds me of my friend, Grace. She is dating a REALLY awesome guy, Erik. He is so cool, and sweet, and hilarious, and just perfect for her. They had been "casually" dating for a few months, and had worked together for 6 months, when his ex-girlfriend started calling her. They were still on a shared cell account, and his ex got ahold of his call history. She told Grace that he said she was fat (sooo untrue), she was slutty (again, totally untrue), they were still together, a bunch of lies. And, she told Erik that Grace was dating some one else, and told her she didn't even like Erik. Obviously, she is a pretty disturbed person. D=

If the guy weirds you out, by all means, cut off contact with him. But, if you're basing this on his ex's comments, if I were you I would at least give him a chance to defend himself.