Tips on how to regain self confidence and get back out there after being in a long term relationship

I appreciate the question very much because it's a very interesting, important and meaningful one. When we talk about self confidence, it's basic to speak first about where it comes from. The main source of confidence in ourselves is normally our own self esteem (the way I like / love the person that I am). It means, as long as I love myself more I will be more confident about the person that I am. This is the main root to work on to gain self confidence.

How to achieve this? Well, to improve our self esteem there are different ways to start:

1. You can look at the different contexts of your life (social life, family, career and personal life) and see if there are problems regarding any of them so you can change the things that you don't like, so you can feel better with yourself. 

2. Try to be more assertive and let the people know what you think, in a polite and respectful way, and say "no" when you want to say it. When we avoid confrontation or we are scared of hurting others, normally, we tend to say yes or accept what is unacceptable for us, so our self esteem suffers due to that. 

3. Try to speak nicely to yourself and judge your experiences fairly, not trying to be perfect or having unrealistic expectations. Notice when you are being harsh on yourself and stop it, and imagine that you are assessing an experience of a friend instead of your own experience and see if your assessment is the same or not. 

Another very capital thing that we must not forget is the fact that if he did something that was not fair to you and, apparently, not being honest it's something that you can not take responsibility for. That situation is something that did not depend on what you were doing at all. That situation doesn't say anything about your worth as a person. The behaviors of others are not under your control, so it's only talking about their own worth, you shouldn't blame yourself in any way for this. 

I know you will be able to move on and believe more in yourself. Wish you the best.