I am sorry you are going through this! Breakups are so tough. Based on what you said, these are my thoughts. When he said he has too much on his plate, that suggests that your relationship was a low priority to him, as he likely could have given up something else. When he says he can't be consumed with thinking about you, that tells me he is being selfish! Or maybe he is just not willing/able to deal with the relationship. Now its hard to say because I don't know if anything else happened (in your relationship).
But it sounds like maybe this came up out of the blue? He could also be making an excuse and thinking "I have too much on my plate" would be a good reason to tell you.
Either way, I don't have a great impression of this guy. Obviously after dating him for a year you feel differently and I DO understand why you are devestated. But, you should try to think if you want him back because you miss what you thought you had or what you really had. If you really have a guy who thinks you are the first thing to go on his filled up plate, then you need to pick yourself up and believe that you will get someone who would never leave you no matter how much he had on his plate.
JayDee-I like that confidence building! Jenni, be sad for a while and grieve, and then get yourself back out there!