YOU MUST CHOOSE HOW YOU DEAL.
The fact that you feel betrayed, doesn't mean that you were truly betrayed. Sometimes the disappointment we experience is as a result of the unrealistic expectations we have of people and situations; or our orientation about how life should be lived, without paying attention to the mentality of the people with whom we're dealing; or the affinity we feel towards people which we unwittingly translate as the entire story of those people.
Before you hold the view that you have been betrayed, make sure that you're not experiencing self sabotage - something I love to call the BETRAYAL OF SELF.
Life must be lived deliberately. Anytime you don't count the cost of what you're getting into before plunging in, you are the architect of whatever misfortune you encounter. You have exposed yourself to a more uncertain gamble. The likelihood of things working in your favour is far slimmer, and you should expect the worst scenario. God forbid and Tufiakwa! don't and can't stop that day from coming. It will come, and when it comes, don't blame the one who you feel has offended/betrayed you by his or her actions. Blame yourself for not seeing that the situation is a necessary and unavoidable consequence of dealing with this person without due diligence.
Believe for the best in people but stop expecting people to change just because you're good to them or because you gave them a chance to be your definition of better. You can't pay people to change.
Stop counting on what people say. We are not what we say, we are what we do and we become what we do. So don't accuse people of messing up the chances you gave them when you should have seen the conclusion already, from what they do.
Stop depending on the vow of a person whose lifestyle clearly shows that he/she is not capable of keeping their word. There are people who always feel they have justification for not keeping their word, and there are others who keep their word no matter what it costs them. The latter might not be so packaged and they don't make bogus claims, but they are honorable enough to keep their word.