It's really easy to call CPS out on a family. It's happened to us. The case was so bizarre that the cops were ready to call it harassment...but the CPS worker still had to waste her time coming out and investigating and doing all her stuff, just because someone decided to call CPS to say that my children were home unsupervised and there was an infant in the home. Funny thing, the first time, they were with a 16 yo babysitter, the second time, I was home. And my youngest child is 6. In addition, we are not Asian, as the caller indicated I was. That's about the time the cops decided that whoever the caller was was just out to get me or crazy, and told me to not worry about it. They actually called the caller to say DO NOT CALL US AGAIN. Who knows what was going on. All I know is that it wasted my time, the cops time and the social worker's time. And it put me through hell for a few days, even KNOWING I was innocent, because CPS can and will pull kids for very little reason on occasion.
If you suspect abuse, by all means, call. But not for a couple of bruises. Children are hurt and families torn up by false accusations of abuse too. You don't have to dig too far into the foster care system to see that.
Your story is what frightens me. I've had friends who have had similar experiences. The one that scares me most is a guy I knew was playing with his kid in the living room of his first floor apartment. The guy had his shirt off. The child was dressed.
A neighbor walked by and decided it looked like the guy was molesting his kid. DFCS (CPS in Georgia) came and took the child and the guy could only have supervised visitation for nearly two months while the allegations were investigated.
That was before I had kids. It was unreal to me, and even though I'd known the guy for years I found myself becoming suspicious of him. In the end, they didn't prosecute, there was nothing to it, and he got his kid back.