Can I take a break?

He cancelled.  At the last minute- again.  He knows I hate that.  I could have made other plans.  I'm starting to get tired of making someone a priority that only makes me an option.
A few days ago he made me so happy.....telling me that he will likely be able to spend a day and a half with me this summer.  He seemed genuinely happy that I was happy.  And I was.
 
And now I'm thinking about taking a break.
 
I'm feeling particularly strong.  I've been exercising and losing weight and getting healthy.  I'm trying to fix myself so I can be confident and go out there and meet someone new.
 
This is a dead end.  I know that.  I've always known that.  But I'm feeling strong than I have in a long time.
 
He will probably email me tomorrow, asking if I fell asleep, or if I'm okay, or even just "how are you".....what will I say?  I'm thinking about saying "let's try again next month."