Along with your computer choice you should also think about getting a taser gun to keep her from taking your new computer.my fiance has acquired it and left me with a £400 Dell laptop.
(hands off woman! lol)
I have used all three 13", 15", 17" but only own the 15" MBP. The thing is that everyone's opinion is going to be biased and it does depend on what you are doing on your computer and what's more important to you; the portability, screen size, matte screen, faster performance, etc.
Since you do have a 13" in the house, see if you can borrow (regain) the use of it for awhile so that you can test out how the 13" will hold up when you use it for your most frequent computer tasks. That would be the best way to know for sure. When I used the 13" and 17" I knew they weren't for me.