My sons dad called cps on me what do I do?

He had a tiny lil. bruise on his eye and when I noticed it he told me the wall hurt him. its either that or he got it from my two year old step son. I never hit my son. I would never allow anyone to do so . the Dr at the hospital says its very questionable for child abuse and so did the cps lady I talked to. I was a victim of my sons fathers abuse. I had a restraining order but dropped it because I thought he'd be a good dad. I let him have fifty percent custody and ever since then he's been trying to take my two year old baby away. I have filed harassment charges on him.