How do you deal with a friend that always wants to hang out and doesn't have a clue?

Ever since a friend of mine came back home from college, he asks me several times a week to hangout and every saturday and sunday he asks to get breakfast which we do sometimes (he has no job atm), while I work 6 days a week and don’t have the time to see all of my friends let alone him these several times a week.
He also doesn’t seem to have a clue how to interact with people socially, as he cannot seem to get over his girlfriend of 2 years ago who has rejected him since their breakup multiple times, as well as being rude and ungrateful around my friends he has recently met. He is constantly late to engagements we plan together.

I feel bad just not responding to him, and I am at my wits end. At the same time he is an old friend, and so I always respond to him and have to tell him “no” repeatedly, then explain why because if not he will certainly ask. I do try and see him once every week, but he has nothing to do.

What can I do?