I need to talk. Please, answer

I'm and Italian 40 years old "girl". Two years ago, after what I thought had been 10 blissful years of marriage, I became attracted by a friend that I used to run with (we belong to a running group). Besides running together, we had exchanged email addresses and started chatting on computer, thus getting to know and appreciate each other more and more. Nothing physical happened for about a year. Let me tell you, before I go on, that for 13 years, together with my husband, I belonged to a very strong religious community (Latter Day Saints). Our whole life turned around the church, but I was happy about it. My husband's job kept him out of town during the day. We hadn't had children, notwithstanding all our attempts (included in vitro fertilization and adoption, for which we were supposed to wait two more years). Anyway, when I figured out I had fallen in love with A. I candidly talked about it with my husband: probably, had he shown some jealousy, things might have ended differently, but he acted as if I were ill, and in a way I felt myself as if it were sort of a bug that I couldn't get rid of. In the end, I decided to take a trip abroad and spend a month with friends belonging to the same religious group, also getting psychological help. When I came back I though I was whole again, but the very next day I felt compelled to go and find A. He had had a rotten month himself, unsuccessfully trying to forget me, so in the end things got even worse and our relationship became also physical, leading, in about 6 months, to breaking up with our spouses and going to live together. Nevertheless, things haven't been exactly perfect since then: daily living together brought up the sides of our personalities that hadn't shown during our "perfect story", but the main reason was, and still is, that I can't help but live with huge feelings of guilt for having abandoned a man that loved me with all his heart and adored whatever I did, plus my religion, whose standard I wasn't living up to anymore. I actually don't miss neither of them, I just feel like sh** because of what I did: this makes me act childlike toward A: on one side I feel that he's all that is left in my life and cling to him constantly, making him feel pressed and breathless; on the other hand, I constantly feel that I should end our relationship, but I love him deeply: it's just that I can't live this story in a relaxed, serene way. I'm aware that in no case things could go back to what they used to be, after all I don't want them to, but still I can't help acting the way I do (feeling bad, making him sense it, and, thus, questioning our relationship and putting it to trial). I need his CONSTANT attention and love, to be cuddled constantly, and if, for a day, I feel like he's not paying attention to me, I start making up stories that hopefully will get him jealous, so that he's interested in me again. But these things only make him angry… I didn't use to be that way with my husband at all, but after all my husband was dependent on my love as much as I'm now dependent on my new partner's love (infact I find myself saying and doing many things that my husband used to tell me, live "I need you", or "I can't live without you"). I got to the conclusion that I'm codependent, but is it possible to start being such from one day to the other? What really confuses me is that I had great parents, who loved and took care of me, but I know I lack self confidence and self esteem, all the same. Please, help me.