My friends might be neglecting their children

Iv'e recently been troubled by our good friends' treatment of their children. They are very gentle, loving people. We used to go to the same church and I worked with the husband. The mother has serious depression due to abuse that she has suffered. She has an extreme aversion to cleaning and the husband doesn't clean either. Their house has looked like trash heap for the three years I've known them. Since the one year old was born there have been old dirty diapers on the floor and the baby just crawls around in it.
The mom has been doing better with her depression by staying very busy. With 3 children under 6 I know it's hard. The oldest has always been very mature, but I'm starting to find that a little disturbing. When he was three he had to have serious dental work done. Two weeks ago he told me his teeth hurt and the adjacent teeth were obviously very decayed when I looked. The mom looked like this was the first she'd heard of it and said she didn't know what to do because she'd missed appointments with every dentist in town and couldn't go back.
They used to force feed their children and shove a lot of food into their mouths with them crying hysterically and they stopped after I had a few kind-hearted conversations about this. When they were here the baby dislocated her wrist and it was very painful. Mom wouldn't take her to the ER. The father popped it back in saying it had happened before. It was obviously because he usually picks them up by the arm and moves them sort of like luggage. I talked about how loose babies' joints can be and they said they already knew that.
The family has been using our bathroom for a year. The father started a remodeling project he could not finish. My husband helped to finish as he was a framer, but he injured himself and could not continue. Since then their bathroom has not been worked on and they have no bath/tub shower. Previous to that their children were always relatively dirty anyway. They have huge mounds of clothes, but the children wear the same clothes for 3+ days.
I feel bad because I really love those kids and the parents. We tell them to bring the kids over if they ever feel overwhelmed. I feed them and bathe them. They have so much fun playing with my son and his toys. I would never just report something like this. I'm positive there is no physical abuse going on. I honest to goodness do not trust CPS. I think more and more problems with that agency will be exposed.
I'm not standing in judgement. I've never been perfect. I don't know if I can offer more support without enabling the situation. Could this be significantly harmful. I need to help them.

Okay, You are a saint and are having a huge impact on their lives. Not sure there is much more that can be done.

Sure you can get intervention and maybe the state will take them away but considering how that worlds out for the kids not sure it would be better.

But seriously you sound wonderful,your husband too.

Thank you for the compliment. I just want to make sure we're doing what's best for them.