Don't feel stupid. You are a good person and you wanted to help. Sure, you had in mind that you were helping him to be better for you, as a couple, but we all sometimes become blind and don't realize we are grooming a guy who is not doing his part in helping us be better.
Just end it already to save yourself time and headache. You still have feelings for him, so it will be hard for a while, but eventually you will move on, because now you know that this relationship would not go anywhere and the hurt would be much bigger, even 6 months from now, when he would/will get promoted, make more money and then dump you.
On your next relationship, watch out if the guy is giving back the same you are giving, which is seeing your potential and helping you grow. I read once something that said "there is nothing more rewarding than seeing your partner shine". If the guy honestly cares about you, he would also help you
out in growing and being better than you already are.
Printer already stated those facts, but they show how little he has to offer:
1) you are beautiful (you really are!).. he is probably not .. so he is below you
2) you are educated .. he is not ... he is below you
3) you are making good money .. he is not ... he is below you.