That's probably the best plan

I think you've got the best plan now, let her know you love her, it's not your idea, you know it's unfair and stupid, it's not your fault, it's not her fault, but you'll have to pretend to just be friends (or less) to keep them from doing even worse. Don't tell her to go find a bf her own age, that's as bad as telling her you don't care, and it supports the shit-headed attitude that 'her own age' is the only 'right' kind of bf she should have, and you know that's the attitude that caused the whole situation in the first place. If she comes out of this believing that you care about her, despite what others might say, perhaps in a few years she'll be an ally to all of us and help cure this sickness society has. Maybe, even, when she's 20 she'll help you meet another 10yo to fall in love with (and probably lose). Anyway, your plan sounds like the best option to me.