Most Helpful Guy
You should let him go. You obviously have him way at the bottom of priorities. Nobody is busy 24 hours straight. If you can't make time for a minute text and he slips your mind days at a time then you need to break up with him.
Most Helpful Girl
Given the title to your question it sounds like you've already decided to break up with him.
Put the poor guy out of his misery and just invite him round and tell him everything. Or are you waiting for him to lose all patience and just blow you off?