((((((((((( Impala ))))))))))))
There are folks in the world who just can't handle relationship responsibilities. And then there are folks who don't KNOW how to handle them. Whatever realm this person falls into....it's obvious the fallout has hurt you and I'm sorry about that.
When I have fallen into that situation, what I've done is allowed myself to be angry, mad and hurt. Then I licked my wounds and told myself that this is a lesson learned. I picked myself up and moved on. I put the relationship away after dealing with the aftermath.
It's not an easy thing to do when one feels they've been wronged and when they don't understand why something has not worked out in the way we thought it should work. But it's what needs to happen in order to move on and grow from the experience.
Time will make the pain lessen. Again, I'm sorry that you are hurting from this situation.....it's never a fun thing to go through.

sabby