YES! YES! YES!
No matter what he tells you or what you’ve made yourself believe, he is wrong, period. I agree, looking through your significant other’s texts is not exactly the greatest exercise in trust or honesty. But so what? You did it! Who cares? I would almost put money on the fact that 99% of people have at one time or another looked through their partner’s phone. And it is usually out of sheer curiosity. Even I will admit that I have done it before. But I’ve never found anything that I find the slightest bit suspicious and more often than not, its pretty boring and predictable. And thats how it should be. Finding out that your husband has been texting with a girl who you’ve never heard of, must be a devastating experience. So whatever you do, DON’T FEEL GUILTY! Don’t buy into his crap.
I know you feel extremely insecure right now. It must feel like the world has fallen from under you. But really, dear, it doesn’t have to be such a big deal. At the end of the day, consider the facts; the only thing you know for certain is that he has (or had) a friend that was a girl and that they were texting to one another. That’s it, and that’s not such a big deal. But why are you making it into such a big deal?
Probably because your marriage and your husband are the center of your life. And while they should be it does not mean that you should loose your own identity and forget that YOU come first (at least until you have some babies, and then you have a tie 
) Stop relying on him for your happiness!! You must find it from within. What are the things that put a smile on your face that have nothing to do with your marriage? Before you met your husband, what were the things that made you feel complete?
Don’t waste time thinking about this issue, which, at present, you can’t do anything about. You know that right now you are at your lowest low, its a horrible place to be. Do you really think that your husband will be the one to grasp your hand and relieve you from your pain? As much as you would like him to, based on what you said above, I am certain that he will not. You are the only person you can rely on right now. Look to some good friends and family too, people that are on your side only. Focus on making yourself happy and healthy again. Become independent. Then you can worry about your husband and his possible infidelities.
As much as you think this issue is about your husband and his “friend” and their text messages, it is not. It is really about you. It is about your self-confidence, your self-worth and your personal strength. The absolute worst case scenario is that you loose your husband. Right now though, you are loosing yourself. And without a doubt that is much, much more tragic.
As a side note, I should say that what the others said above is right. Once you become confident and independent he will come back begging on his knees. This has been tried, true and tested. But don’t do it for him, do it for yourself.
