Re: sex breakdown
**I didn't realize this had been necro-bumped up by 7 months. Feel free to delete unless the OP is still around**
I think people tend to take their own behavior for granted when gauging a difference in their sexual experience between two partners. To a certain extent it makes perfect sense; you and person A have mediocre sex while you and person B have amazing sex - it's natural to attribute the difference to person B.
However, just listening to your description I would be willing to bet that your behavior with your husband is far and away different than your behavior in your affair. I can attest first hand to just how much of an impact perception and attitude have to a woman's experience of sex. Take a serious look at how you perceive your husband, his penis, his prowess etc. versus your perceptions of your former lover. Continue with your own behavior - are they behaviors that you exhibited with your lover that you wouldn't/haven't repeated with your husband?
In terms of orgasms, I think you should again move some of the attention away from your partner and towards yourself. Sexual maturation, when it happens during adolescence, is when exploration and masturbation normally develop. You learn about your body, how it reacts/tastes/smells. What turns you on and off etc. The more involved this process the more refined the sexual side of yourself becomes. If you had never had an orgasm before you met your husband I'm assuming that means you've never spent considerable time exploring your own sexuality, your own body. Teaching yourself how to orgasm, how to enjoy different kinds of touch. If you won't invest the time into develop your own sexuality as a person (aside from your sexuality as a partner even) how can you be so critical of your husband? It sounds like you're putting all the burden of your pleasure on your husband and that may allow for some hot affairs but for long term, satisfying sex you have to pay as much attention to yourself (if not more) as you do to your partner and as your partner, in turn, pays to you.
Reread your post if you have a mind to. Pay attention to your early description of your husband. He was a considerate lover, patient and focused on your pleasure. He brought your first orgasm out of you. Then after your affair, confession and therapy your sex life improves - he's trying to improve his technique etc and your response is disappointment. To complain about the size of his penis - something he can do nothing to control. I don't know what this shows, I have no credentials to make assumptions or to validate them if I did. Doesn't he deserve the same patience and consideration he showed you? I mean in reading your post I do feel empathy but for your husband.
In terms of penis size, that's a choice you need to make. It's either enough or it isn't. As advice, remember size is relative. If his penis isn't big enough to fill your vagina then maybe you need to find a tighter place to put it (although do NOT just drink a bottle of wine and have a go at anal sex).
I would pick a fantasy or an act that you've never done. Something that is separate from your affair - just between you and your husband. Female ejaculation, fisting, anal sex etc. Doesn't matter what it is as long as it is something you are interested in that allows you to grow your relationship with your husband and doesn't put him in the shadow of your affair. There is a whole lot of sex to be had, I'm sure there's something that can lead you to firmer ground with your husband.
Best of luck!