As a couple of people have written, the other guy giving your wife reasons to choose him over you is very troubling. That's home-wrecker behavior. Definitely something to bring up with the counselor, IMHO. How did your wife feel
when he talked like that? Defensive? Confused? Angry? Sad? But that's for counseling.
I'm an extreme introvert and honestly don't need ANY friends other than my wife (hmmm...says the guy who's talking to strangers about his problems). She DOES need friends. I need to figure out how to be a part of that part of her life while still giving her space or if we make it through this crisis it will probably just happen again...
Again, IMHO: it may be necessary for you to grow. I'm an introvert, once an extreme one, but I had to pop my shell a lot in the past years. (Open up or die emotionally, in my case.)
Often an extreme introvert has trouble expressing emotions. Recognize that your wife probably needs more emotional nourishment. I know that my first response when I was married and in my extremely in-turned phase would have been, "I do
connect with her emotionally!". But looking back I realize that what I considered emotional connection was actually pretty weak and unsatisfying. If there are ways you can open up more with her then you must do that. Talking is a gateway, but laughter and tears in each other's arms are better. But maybe you are already there, I dunno.
Another way you might consider growing is to step outside your comfort zone as an introvert and go with her to make friends. You should ask for her help -- she would probably love to help you meet people and learn how to relax and enjoy being around them more. If that's possible, a bunch of things might happen: you will be participating with her as she gets the socialization an extrovert needs; she will be helping you and helping each other brings couples closer; you may have good shared experiences that she (and you, eventually) will cherish; and she may feel less isolated and pressured (it's hard being the sole relationship provider for your spouse).
This is all stuff for you, but there are also things an extrovert needs to do too. She's gotta pay attention to you and use a kind of awareness that doesn't necessarily come easily to an extrovert. She has to figure out exactly what she feels about what happened and why --the kind of self-examination which, again, doesn't come naturally to an extro.
Your counselor should bring these kinds of things into the discussion. If you're feeling overloaded and "beat up" at the session by hearing about a lot of things you
need to change, then override your keep-quiet nature and say so -- calmly, calmly! A good counselor should recognize immediately when you're approaching overload. Being challenged and being overloaded are different.
Anyway. I kind of feel like this is a know-it-all post on my part, and I hope you don't take it that way. My sympathy is very much with you. My mother is an extrovert who learned introspection, and my father is an introvert who learned to socialize...they're 87 and 95 years old, and one of the easiest and happiest married couples I know. Go for it!