I believe that there's a lot of stress in your household right now. It probably was a good thing (for both of you) that your wife left with her nieces for a few days. Not a huge amount of time ~ just a little break in the tension. I'd recommend that you try to look at it that way and let it go.

Do share your feelings in therapy this week. That should be very invigorating for you. Just remember to follow the rules, respect space & don't swear every other word. You'll do just fine. Therapy is work for everyone involved, try to remember that.