I stopped reading after you said she was 18.
Not to be rude or blunt, but girls/women don't know their head from their ass when it comes to relationships/what they REALLY want/self-identity/etc til at least their early twenties. Ofcourse there can be exceptions, but I've yet to see or hear of one myself.
You're young, handle it at your maturity level and hope for the best. You already said you know the odds, but you won't believe them because you're blindly involved in this situation, duh. We all do it.
Imola Red M5 | Imola Red Interior
GT Exhaust, Custom BC Coilovers, 19x10 + 19x11 Rial Dayonta Race, Michelin PSS
Daily: 335i M-Sport Alpine White / Coral Red
Too many mods
'04 E55 AMG
'01 330Ci Titanium Silver / Coral Red
'96 328i Jet Black / Black