Hello and thanks for using Justanswer.com! I hope you don't mind that I've switched us to Q&A mode -- I'm having difficulty getting answers to post using "chat" mode this evening. Hopefully that won't be a problem here.
First of all, I'm terribly sorry to hear about the emotional affair your husband had and how it's impacting both your relationship and your ability to attend the church you love without thinking about it. What's unfair about that is that when you go to church, you're going there for spiritual fulfillment -- not to be reminded of any personal relationship issues that have caused heartache. I imagine that's very difficult for you and cause for further resentment.
It's very normal for you to feel various strong emotions at once while going through this. Anger at the woman from your church and at your husband for allowing this to happen. Grief over the loss of what your marriage was prior to all of this happening. This is not to say that it can't be rebuilt, though, and that trust cannot be established again. It sounds like you're already on the right road in that he's working hard to cease communication with this woman and making you the priority in his life. I'm also glad to hear you're working through all of this in individual and marital counseling.
I wish I had an easy answer for how to put all of this behind you. However, as I mentioned before, in many ways you are grieving. Grief is not an easy or quick thing to work through and unfortunately tends to crop up at unexpected times in unsettling ways. The good news is that it will get easier. Continue doing what you're doing (counseling, spending time with your husband, making efforts to connect with one another and show your love for one another) and remind your husband that expressing your feelings about all of this -- as difficult as it may be for him to hear -- is only going to bring you closer in that it allows you to have open, honest communication with one another. Ask him how he is feeling as well. Talk about what might help you both to feel more secure in your relationship and closer to one another.
I do wonder if attending another church would be easier for you. I understand it's not what your family wants, but perhaps you could try another church periodically to see if there is another that is an equally right "fit" for you and your family. If not, is there another service on Sundays you could attend (earlier or later)? Lastly, you might try a cognitive exercise to refocus your attention when you find yourself thinking unwanted thoughts on Sundays. When they creep into your mind, you simply tell yourself, "No" or "Stop." Some people find a visual image helpful (a stop sign or a steering wheel, for example) followed by a pre-determined phrase you've chosen to help you through that moment. This phrase might be a reminder of your husband's love for you. Or it could be a reminder of why you're there and how important it is for you to focus on that instead. Experiment with self-talk to see if there is something that helps you through that moment and leaves you feeling in control of your thoughts / feelings.
In the meantime, I'd suggest you begin journaling if you're not already. Sometimes writing down all of our feelings during difficult times can help to sort through it all. Reflecting upon those pages later can help us to see that we are, in fact, making progress (even when it feels as if it's a snail's pace!) I wish you the best of luck with all of this.