HELP!! i broke up with my ex and might have regrets...?

Of course you regret it. Everyone regrets it. Psychologists even have a name for it; it's called buyers remorse. Basically what it comes down to is any time you have to make a big decision you will always wonder if you made the right decision. This can be anything from buying a car (did I buy the right one? - hence the name buyer's remorse) to emotional decisions. If you were having big problems you made the right decision. If it was little things that can be solved and you want to try again then try again. Remember a relationship is work and if you're not willing to work at it (both of you) then you've already lost.