*Huugggsss*
I'm so sorry for this Miss Rose, I was reading the thread last night through tears. I'm not sure why it got me so hard.
Your sister said that her son was a "good boy" before he met this girl, but what she really means is that he was a compliant boy. As soon as he found something worth defying her for, she dropped him like a hot potato. His decision was wrong of course (even if the baby isn't "his", they must have behaved in a way that he would believe it could be). But as you said, none of that is the child's fault and your nephew has decided to raise him as his own. It sounds like he's making the best of the situation, and currently showing a lot more maturity than your sister is.
The reality is that, even if she knew it was 100% true what she's saying about the baby being someone else's, yadda yadda.....she should not be spreading it all over town and she definitely should not be involving her young son in it. That shows a staggering lack of spiritual maturity. It sounds like it's all about appearances for her, if she can convince everyone that the baby isn't his then she thinks that will make herself look better. And that seems to be mostly what she cares about right now..... LOOKING good, not actually BEING good. There is a huge difference, and it's stressful situations like this that reveal a person's true character.
Your nephews are being abused, in my humble opinion. I question if the oldest even wanted to join the military, that may have been purely his parents idea. And I think you are right that your sister was using him for emotional support in her difficult marriage. The kids are clearly being controlled and told what to think and how to feel, and that is a very heavy burden for a kid to bear. Thank God that you and your husband are there to offer support, I do believe that He has and will continue to use y'all in this!
Anyway......I'm actually going through a similar situation with a friend of mine, she is the worried Mom of a good son who made some bad choices. But she has been mostly biting her tongue and opted to show love and prayers. It has been hard on her, but God is working in the new little family and we are already seeing fruit. I believe God can and will do the same for your nephew if he keeps seeking Him <3
And in the meantime.....prayer works, God's got this, and Bless you and your husband for being a stable, Godly influence in your nephew's lives, they seriously need that right now! I will pray-