He doesn't do emotions. But he knows he can tells himself that all he likes and he won't believe it, because when it comes to her he does a lot of things he thought he'd never do.

She is alive, just as he'd thought (hoped).

He is alive, just as she'd known (hoped).

And John is thoroughly exasperated with the pair of them for putting him through that.

Mary just looks confused.

Their first meeting after death goes much as Sherlock had imagined - much slapping and shouting and someone crying (he thinks it was John, no it wasn't him).

And it ends very differently, with Irene seeming to roll her eyes at a non-existent God and pin him to the wall.

Yes, she's definitely alive. In fact both of them are, even though two of the four in this room are legally dead and the other two are blushing so hard they look like they want to be.

Because death is a concept both Irene and Sherlock understand. And when Sherlock Holmes understands anything it is even easier to evade.

Death is just a perception.

And right now, both of them are very much alive.