My wife left me suddenly

I’m not really sure where to start. My wife of three years left me suddenly recently. She’d been spending more and more time with her sister and didn’t seem really interested in spending time with me. I told her I was feeling unloved and her response was “I can’t give you what you want”. She walked out and went to a party with her sister and I didn’t hear from her for 24 hours. When she came home she told me she’d been up all night talking to another guy who “just gets her”. She told me I needed to fix a bunch of things to make the marriage work and I tried to show her I would do anything she asked. Then she told me I was trying too hard, all the while she was going out to her sisters house and spending time with this guy who gets her. Next minute she invited me to a park and said she doesn’t love me and she wants every day to be about herself.
Three weeks before this we were sitting in the doctors talking about how to get prepared to have a baby. We had baby names and everything. She seemed to just change the night she went to the party. When she came back her mannerisms were different, her desires, her interests. She was like a completely different person inhabiting my wife’s body.

While I’ve sought to try and understand how my life could just fall apart so suddenly I’ve had a lot of people tell me she might have NPD which is why she behaved the way she did. I guess I’m having a hard time understanding what that means and if it could be true. Either way it doesn’t make it any easier. All I do now is look back at every tiny thing I did wrong and wholly blame myself for ruining my marriage and driving her away. It’s been six months and I’m still dreaming of her every night and thinking of her every day. I’ve tried everything I can to get past this, therapy, exercise, meditation, medication, talking to friends, dating other people, but nothing works. I miss her every day and just want to curl up and cry all the time.