Anyone have experience with CPS?

I would really love u ladies to help me out, I'm in a bind with baby mama. Apparently she has called CPS on me and accusing me of things with my fiance's 3 yr old daughter. I love this little girl to death, and she loves me. I mean she calls me mom, why would she call me mom if I'm doing something to her? And when she's over at our house she calls her mom by her name, what does that tell u? I've tried to make a good relationship with baby mama but she is making it so hard especially now with this crap she's pulling. I don't know what to do :( I would never do anything to that little girl. I may be just step mom but I don't have to give birth to a child be a mother.

Is there anything I should not say to CPS? And what should I say?