Hi Anthony - welcome. Hopefully you can get some help and comfort here. We'll do our best!
First, there is hope for your marriage. You can work to repair it, and even make it better than it was.
Second, what your wife did was wrong - you and she both know it, especially if she is as moral as you claim she is.
Third, is the friend you stopped talking to the same one that she kissed? Your post doesn't make that very clear. I am assuming it is. If so, you should be asking yourself how good of a friend is this, if they will kiss your wife passionately (and not, at the very least apologize!)
Fourth - I highly suspect that more than just kissing is going on. This will be something for you to find out, however. If you do find out, there is a lot more you must consider.
Now, however comes the work. Your wife made a claim you should pay attention to: she said she wanted to see if she had any passion. She won't apologize - and it seems that you "drove her to this."
No matter what you did, you did not DRIVE her to do this
- she made this choice on her own. She could have taken an entirely different step than she did. She could have come to you to see if you could work on bringing the passion back to your marriage.
I'm going to borrow some text from another thread by one of the coaches who posts on this site. It will give you a good idea of why things have changed for you:
Think of the love in your marriage as a campfire. There are actions you can do to stoke the fire and make it hotter--those are Love Kindlers. There are actions you can do that are like putting water on a fire--some are like dribbles out of a holey bucket, and some are like dumping a big old bucket of water on the fire. Those are Love Extinguishers. When you two first met there were no Love Extinguishers because you weren't living together...and at the same time there were TONS of Love Kindlers. Think about it! People in love tend to spend a lot of time together; they talk to each other and get to know each other--and they actually stop and listen; they do fun things together like go bowling or take walks; they look good for each other and flirt.... See all those kindlers? And sure enough, the fire of love blazes and you get married. Then enter some Love Extinguishers. Maybe she's not a great money manager (or the opposite, a controlling penny-pincher); you work many hours you don't spend as much time together; when you are together, you watch TV and don't talk anymore...and the Love Extinguishers are dribbling on the fire. Then more Love Extinguishers--kids are born and there's even LESS time together; she gains some weight and you wear sweats; you yell at her about bills and she disrespects your job; you want sex and she doesn't feel connected to you so she resents it...and the Love Extinguishers are getting to be less like a drip and more like a downpour.
(BTW - thanks coachCJ -affaircare on here)
In essence, what's happening is that your marriage has lost some of its appeal - this happens. Things get mundane, routine, partners start to take each other for granted, they don't really talk things out, etc.
Here are some resources that I often recommend to people:
A couple of invaluable quizzes that hopefully you both can take (they will get you both talking in ways that you rarely do): Emotional Needs Quiz Love Busters Quiz
And two other resources for pure information: Affaircare
and a related blog: Portland Infidelity Examiner
Keep posting here for a while, ask questions, make observations, and keep praying. There is always a way to create a stronger marriage!