If this happened before then I suggest you delete and block him from facebook and don't "reach out" again. You two were not meant to be life partners. If you were, "this" wouldn't keep happening.
You'll hurt for a while but you'll soon enough be indifferent to any feelings to him if you go no contact and don't creep his fkfacebook page. If you or he are married to or otherwise involved with innocent others then leave your affair partner alone to deal with his marriage and you do the same. If you're not married then find someone free to be with you for more than just sneaking away to screw.
Learn about yourself and why you fear being alone or committment which leads you to have secret affairs where you know you cannot commit to him/her but you still stay with one so you don't have to be alone.
In other words, You have issues that you should work on so this does'nt happen to you again.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion