First of all I want you to know that you nailed it. I was worried that it's length would make it a painful read, especially after having just came home from work, but it wasn't at all. I think the ending was exactly what you want. Any more explanation would have been as likable as explaining a joke just after telling it. You know what to tell, and what not to tell; what to hold back, and what to show. You know how to give a person's imagination something to do to fill in the blanks. Just, really, be proud of this.
So the criticism that I have won't be related to the plot except for one tiny thing;
It was his dad. Lance Montague's reputation ensured that his son had front-row seats to what was quickly becoming the second worst moment of his life, even from beyond the grave.
...i don't think you should have gave it away here. You pretty much telegraph at the beginning of the launch sequence that you are going to kill off Diane, which dampens the suspense. If it wasn't for the conspiracy bit, this would have soured the ending entirely.
Your prose is good in the sense that I didn't have to make an effort to read and keep reading, but at the same time I feel it is a bit unpolished. It feels like you fall back on cliches a lot. The dialogue also isn't especially polished, and has the immature melodramatic feeling of the dialogue of shows on the CW. A good thing to try and do with dialogue is to read it alone without context from the rest of the writing and see what type of characters you end up with. Doing that makes Harry look like a little snot, meaning his character is very dependent on inner monologue.
The other thing that I couldn't help but notice is how, despite being distant in the future, you could easily transport what is going on into any decade in the late twentieth century and nobody would notice. What I mean is, it does not feel like this takes back very far in the future at all. Any time a character looks back to the 2030's or whichever, it sticks out like a sore thumb because nothing seems like it belongs in that late a date, let alone later.