Should I date a guy whose ex-girlfriend is 7months pregnant?

I am crazy about this guy I met about two months ago. He swept me off my feet and made me fall for him
before he told me his ex-girlfriend is 7 months pregnant for him. What I find odd in all this is that they dated for 6 and a half years and broke up just two months after they discovered they were expecting. He told me they grew apart and decided split which I find strange because which pregnant woman wants to leave the man she's pregnant for? I wish I could speak with the lady and find out what really happened between them but I'm too scared to contact her. He told me that chapter in his life is over and the only thing tying him to her is their unborn baby. I feel guilty dating a man with a pregnant girlfriend, but should I feel guilty? Should I go ahead with the relationship? Also, what kind of a man leaves his pregnant girlfriend?
[Source: Lindaikeji]