For one, I'm really sorry, that's just an awful situation.
People literally travel to another continent to adopt kids so only meeting the kid once should be fine.
For one: talk to your fiancee. This is obvious, but i didn't want it to be left unsaid.
As far as if you'd do a good job, I'm almost 100% certain you'd be better than the kid bouncing around the foster system for the next 15 years. Obviously it'd be a lot of work, but I'm sure you could figure it out. Every parent justness started out at some point.
i don't mean to undersell the responsibility adopting a kid is, but if your only concern is whether you'd mess up the kid or not, I'd tell you you probably won't.