Invited ILs on Mother's Day Hike - UPDATE 6, 8,10,11, 14

New screen name for anonymity, been here for about a year. This is 100% my problem, and this post will be longish. Sorry, tl;dr at the end.

Communicating with my in laws is always a struggle. They make plans to travel to see us and their other children who live nearby without asking our schedules, and when we ask for an itinerary they dodge our questions or get all butt hurt that they have to plan their own inconvenient vacations.

I guess when I say they, it's really just MIL. FIL is practically absent from all of our lives. He's her accessory.

She planned a trip to come out for her birthday week, gave us dates for arrival and departure, and the days she wants to stay with us, and asked us to plan a birthday party for her... ridiculous bull shit. On her itinerary she says they would be driving home (12-15 hr trip depending on conditions and route) on Mother's day, so I thought "at least I've got that going for me".

I responded as soon as DH and I talked it over that they could not stay overnight with us, we'd meet with them at the family dinner my SIL organized (purposefully 2 days after MIL's b-day, as far add I know no one has intentionally planned anything for her birthday), and that we might be able to fit them in for lunch the day before they left. She says "ok, that's a shame you won't be able to afford more time with me, especially since I had to take a whole week off work to come see you." More ridiculous bull shit that we don't respond to.

When we don't respond, MIL emails us again to let us know she just looked at a calendar and saw that they'd miss mother's day traveling, so they'll be staying in the area for an extra day. I had a feeling this was her plan all along, but wanted to spring it on us late so we couldn't say no or feel guilty enough to invite her to our private family celebrating. I said, we already made plans for that day, hope you enjoy the day with your husband. No response.

Then I got really sick and turned into some idiot unicorn zombie. I invited her and FIL to go on my long since planned mother's day hike. I am hating myself right now. I don't know if it was guilt, or nostalgia, insanity, or demonic possession. She accepted without taking to FIL, so I don't know what the heck he's going to do.

It's a cluster cuss, and I don't know how to rescind my invitation. DH could literally not give any less fucks about our relationship with his parents, so whatever I do he'll be ok with (unless my zombie unicorn is contagious).

My long term plan was to phase then entirely out of our lives, and I was on track until now. Please, please please help me fix this.

TL;DR : invited MIL on Mother's day hike in the middle of a fit of madness, CTRL-Z! CTRL-Z! CTRL-Z!