I learned how to read music by taking piano lessons as a kid, and I think piano is probably the easiest instrument to start with if you want to go that route.
I would suggest, though, going to a music store and seeing if they have any beginning piano or music theory books- like "music theory for dummies" or some other kind of self-teaching beginner's guide to music theory. The people at the music store would probably have some good suggestions, as well.
Maybe it's just the way my brain works, but I find music theory sort of soothingly logical. Everything has a meaning, everything has a purpose, and it's all very consistent. I'm a terrible musician but by golly I know my music theory.