One of the biggest collapses of relationships I see here and in real life....Is the drastic reduction in communication. Whether it is about sex, kids, finances, or even just the weather.....It is a constant theme.
In your situation, you felt unappreciated and ignored....So you found some one else to talk with. The irony being is that your wife appears to have wanted to be talking with you, but it wasn't happening. Now that you are spooked (and of course she is too) the lines of communication have been opened up.....So what does that tell you about moving forward?
I am going to share I thought I keep in my head for all communication. Whether it is the kids, friends, or business......from the 7 habits...
First understand, then be understood......Making that thought an integral part of my communication pattern has changed how I interact with people and made talks a lot more rewarding.
As for opening your marriage.....I have no recommendation. This is what I will share, I have known about 15 couples over the years that went that route. The pattern was the same for all;
-Nice open and honest first time -start of hidden convo's -start of hidden meetings -eventual divorce
In every single one I have known of. Now that is just my experience and there may be some great open marriages, but IMHO that course is just a band aid covering a bigger issue.