You have no choice but to go down into Limbo. You have to make it work because he needs this. Failure meant he'd spend the rest of his life in jail, that he'd never see the children he so desperately wanted to get back to. You wash up on the shore and you know that whatever happens, it's not going to be good. You hope, with all your heart, that he'll find peace. After everything she put him through, he deserved at least this.
He leads you through the streets, points out the memories they built from. He said never to build from memory and you know his rules come from personal experience. You're worried about what you'll find as you head into the modern looking building. He leads you to his home, the same one you saw in his dreams, and you know she's there even before you see her back. You stand off to the side, watching and looking for their target even though she doubted he was even here. The conversation turns though, to Inception, and you connect the dots even as you ask him to explain. You can't imagine the guilt he's carried around him all this time.
He promises a trade, him for their target, and you want to scream at him. You want to drag him along and force him to come back, to ride the kick up the layers and back to reality. The job needs to be finished, but you don't want to leave him. Still, you do as he says, checking on the target and improvising a kick. His voice filters through the storm.
"Look at you. You're just a shade of my real wife. You were the best that I could do, but you're just not good enough."
You see her lunge for him and you react without thinking, the pop of the gun just as much a surprise as the look on his face when he turns to look at you. You're not apologetic though. You hate her. You hate what she did to him. You know he brought it on himself but you can't blame him. He'd gone too far, but was it worth losing his children over? No. So yes, maybe you got a little bit of enjoyment out of shooting her. The real victory in all of this was that he finally let her go. You fall off the balcony knowing he'll find the last of their team and come back safely. Then he'd finally be able to see his kids, just like he deserved.