From what you have shared, it sounds like this man has a certain bag of tricks that he has found out gets the attention he wants from women, including you. This is all about HIM though and what he learned to do to gain attention and praise. What he did "act like a gentleman" with you was part of how he drew you in, but that did not last and never does with people like him. Once you got into a relationship with him you lived your life by "his" control and he did what HE wanted which in what you described is he goes out and drinks and practices his flirtation tactics on other women AGAIN to get attention. Actually, he may even have a problem with alcohol and that will take precedent over you or any partner he is with. All your arguments with him revolve around how you do so much for him and he doesn't really do for you. The reason is because he doesn't have it in him, he CAN'T play that game with you, it was NEVER about you, it was always about what HE WANTS.
It has not been very long since you broke up with him, you are still "wanting" that something you never got with him and you are questioning that maybe it was your lack or your fault when there was never anything you could do to get him to be able to be what you had wanted from him, he doesn't play that way and never did and NEITHER did your exhusband. Neither man was capable of actually "loving" and appreciating you either, they only learned how to play a game that got them what they wanted from you it was NEVER something mutual or conducive to being a relationship that was a healthy give and take.
When your ex ended up cheating on you with your best friend, I bet both these individuals had always been about themselves but you just did not see it that way. You were probably attentive with both of them, but that was not about YOUR needs or actually considering YOUR needs and feelings. You think you might be doing something wrong when you blocked him, but you are conscientious and that's how conscientious people think. But what you have to come to realize is that HE is not conscientious like you, and that is why it was so easy for him to move on. All he did was play you to where you believed he was conscientious like you are and HE JUST ISN'T and neither was your ex-husband or even your friend that was so willing to cheat with your ex-husband.
I can be challenged with this myself Deyla. I have said many times "My wheelhouse doesn't work that way" and that's the truth in that in being conscientious I tend to care more and consider the other person's needs more and that sets me up to be even more hurt when that other person fails to respect me and ends up taking something from me that is important to me, including my trust. The reason you fear running into him is because YOU CARED, but he doesn't and he can HURT you because of that. What is at risk is your sense of self esteem and self worth, he HURT YOU and NEVER really considered YOUR FEELINGS. Often the biggest problem when someone is conscientious is that person tends to keep thinking the person who is hurting them will some day CARE and appreciate. Well, THAT is expecting that other person to have something he or she just doesn't HAVE in them like you do. That's why you feel so disadvantaged around him or anyone else like that that has hurt you. I can relate to struggling with that challenge. People who are users and manipulators can be very charming and seductive and can SEEM to really care and value you as a person. What they really want however is the world to revolve around themselves NOT YOU. That is why it's so much easier for them to ditch you when someone else comes along that they can get adored by. All you were is just someone on their patsy list. Actually, that's the only reason he might call you too, it's AGAIN about him and seeing if he can keep you on his patsy list.
It's hard to be "alone" and when you make a break in a relationship with anyone, it can be a challenge, especially if you are a conscientious person. Yet, being alone can also happen in a relationship too and actually it can be worse in that you try to care and hope the other person will actually care about you, respect you, appreciate you, but you just keep getting hurt. That's why YOU LEFT and you must remember that Deyla, you were unhappy and you did the right thing for yourself. Usually, it's the conscientious person that hurts the most. You see through a very different lens and that makes it hard to see the red flags where you can be hurt.