Can we adopt our nephew from our psycho sister in law?

My husbands brother passed away back in october, about 6 months after he and his wife had a baby. His wife is absolutely psycho! She currently had two children making this her third. She treats her children horribly, doesnt feed them, bathe them, or anything. We used to keep the baby often and she would bring him over in nothing but a diaper and him and his car seat would be drenched in urine and reek. She wouldn't bring diapers and would bring old hard baby formula. He would be filthy with dirt all over and smelt like rotten milk not matter how much you bathed him. We tried to keep him as often as we could and tried to get her help (she was doing drugs and drinking a lot). We think she is bipolar, she loves you one minute and the next she is freaking out and screaming at you. You never know if she is going to be in a good mood or bad. She also lies constantly.

I went to her house a few times and it was disgusting. She let her dog go to the bathroom all over the place and wouldn't clean it. There were flies and roaches everywhere and old food all over the place. It was the most disgusting thing I have ever seen. And she was raising children in this place.

At that time CPS was investigating her and we thought that would help, but nothing came of it. About 2-3 months ago we got in a huge fight with her because we couldn't take it anymore - how she was treating the kids. So she refuses to speak to us or have anything to do with us. Since then my husbands father and girlfriend have stepped in to help out. They have been keeping him almost 24/7. He now only sees his mom a few days a month. Also, during all of this we found out his mom hadn't taken him to get his shots since he was born! So my husbands dad took him to get that figured out right away.

My husbands dad claims to be talking to a lawyer and getting all this together to build a case against her to get custody of the baby.

My question is, is there anything we can do to get custody of him, to become his parents? We are much better of than his dad and have a more stable home environment. We are young and have the money to offer him a wonderful life. We just feel completely lost and it feels hopeless. We're worried that if we get involved we might screw things up completely and ruin his chances to at least be with my husbands dad.

We're worried his dad wont let him come live with us if he were to get custody because he is selfish. He's only thinking about himself and filling the void that he has because of the death of his son. He's also an alcoholic and is always drunk.

Is there anyone out there who has been through a similar situation or could give us some advice?? We just want to give our nephew what he deserves. :)

We live in Texas by the way.

Thanks!