I think what you feel is more guilt than depression. You should be very happy that your wife is willing to take you back. Unless your still mourning your loss.
What happened to you happens to many men and woman. Marriage goes stale,
the drifting apart takes place , you meet somebody exciting who full fills your needs at the time , etc...... Both sexes use each other for various reasons and then, well ,you either continue on with it or end it. It could have ended a lot worse for you. Being ghosted does suck though. I was straight out showed the door without any reason whatsoever. Same as being ghosted. Life goes on. Don’t let the guilt get to you . You should probably get some counseling though.
Best of luck to you.........