Phantom, has the psych delved into your childhood yet? Many people who have relationship difficulties find that it was caused by the role modelling of the parent's dysfunctional relationship. What was your parent's marriage like? Was either of your parents screwed up and with a history of bad choices?
And good for you for seeking help. It can only get better now.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.