dogs

OK, so my little brother has this dog (OK, I have him right now). His name is Koby, he's almost 8 and he is just the best dog. He's a chocolate Lab, he's very well trained and loves everyone. My brother is a... let's say irresponsible hen it comes to responsibility.
Last time I had Koby he was injured and I took him in and got him patched up. At that point I refused to give him back. But eventually I did.
Well my little brother is taking steps to get his life on track. He is leaving for boot camp in June (good for him) and I have his dog right now.
My husband is having a cow over having Koby here. My kids love him and my dog does better when he's here. He's a lot of fun and protective.
So any ideas on how to keep the dog without fighting or should I cave and call my brother?