My feelings are causing a wedge in my marriage. How can I put them away for now?

So my husband is going to see his family in the next week or two. He started a talk with his mother about what they want/need when an emergency happens, and when he goes to see them he's planning to ask where all the paperwork is and talk with MIL about his dad having memory issues. We are hoping to talk his parents into to re-scheduling the memory studies—MIL cancelled because FIL was scared they'd give him a lobotomy. I can't believe this is finally going to happen. I wish it had come sooner. I worry it could be almost too late, but I am thankful.... At the same time, I am having trouble believing it will happen until it actually does.

It really surprises me for as much as his mom has vented to me about the stress of caring for her parents (who are both still alive) and trying to find help for them she seems super in denial about how much it will turn our lives upside down if she doesn't make plans with us for her and her husband's care if she is incapacitated. They live hours away from us, and she really injured herself in July to the point she needed therapy. She wasn't supposed to drive so she had FIL (who has been having hallucinations and memory loss) do it. I've noticed they buy a new car every year.

They gaslighted us saying it's every 3 years (it is not) and their financial advisor told to do it, and DH believed it. I don't buy it. I've noticed FIL's quirky behaviors for 9 years. MIL denied it and even normalized his oddball behavior while it was happening. MIL finally was upfront about it this summer. Guess how long it's been going on? 10 YEARS!

I've been carrying anger about this for a while. I had an abusive family (that I finally walked away from for the sake of my child and husband—as much as for myself). They had gaslighted me through childhood about physical and emotional abuse and even being kidnapped. It's taken years of therapy to work through that and to actually see life for what it is. On top of that, DH didn't seem to get how bad the abuse from my family was until he actually saw my stepfather get violent with me a number of years ago. Then he was right there with my gazillion therapists telling me "this is not normal" and supporting me every moment to set up healthy boundaries. As much as it confounds me that it wasn't real to him until he witnessed it, I will forever be thankful for that. It's part of why I am trying to be as supportive as possible for him through this.

But this stuff has been triggering for me. I know it is human nature to hide things like this when you are afraid and to normalize them. I know dementia is an older person's greatest fear over death. Still, I feel resentful on so many levels...and I feel stupid, too, for not pushing my observations on DH harder earlier (though I don't believe there would have been a kind or even healthy way to do that as he was so strongly in denial until this summer). DH is finally taking action going to visit his parents. Some people here suggested I come with him, but this first time, he asked to see/talk with his parents on his own. I feel that is the right choice. His father doesn't trust me at all.

I feel pretty angry with them all. I feel like our lives could be put on hold or even into a state of chaos, because MIL unrealistically expects us to swoop in and rescue them and until this point, DH was completely wearing rose-colored glasses.... He finally has been waking up since his mom told us about his dad's memory issues and hallucinations. I tell him about my fears. I believe he is listening and will do his best, but I still feel angry about it.

So how can I put these feelings away for now? My anger (and his own at this whole situation) is causing a wedge in our marriage. It's also complicated my relationship with/feelings for my ILs. I love them. I used to call MIL once a week. Now I don't feel comfortable speaking with her, because I'm so angry about this and also scared of what I hear from her next. She keeps getting hurt or sick, and she keeps torturing herself (and keeping herself from having a life outside her home) to take care of her husband. It's like watching a slow accident and not being able to do anything when you actually should be able to.