My Ex Boyfriend lied to me about him having a girlfriend.Then I found out about his girlfriend when I called him. He lied about coming to see me he mad me look bad because he was with his girlfriend why would he do that.

No idea, only he knows why he lied, so ask him.

Why is it important that he has a girlfriend? He's your ex, not your boyfriend.

He's your ex. He's not required to tell you the truth. Why are you still talking to him?

He lied most likely to tell you what you wanted to here, you said coming to see you, so most likely he was hoping to still get lucky with you perhaps.

The question is why are you calling him and why do you care if he has one