Do my husband and I interfere in his ex wife’s current relationship?

Okay. Bear with me here.
Background context: My husband shares three daughters with his ex wife.

Story: My husband’s ex-wife, Lisa (Pseudo name), was in a relationship with a man for a little over two years. When right around May of this year my husband got a message from Lisa with a picture of green panties asking if they were mine because they ended up in her laundry. He told her they were not mine, which they weren’t. My husband showed me this message and my spidey senses started tingling because 1) Our daughters don’t exchange clothes between houses and 2) We knew it definitely wasn’t any of the girls’ underwear as they are only in elementary school (it was a green thong). I looked at my husband and said “oh my god she just found a pair of another woman’s underwear in her home, her boyfriend, Jake (Pseudo name) is cheating on her”. No further communication was had about that as that’s not our life to deal with. Lisa also said nothing further about it either. A week and a half goes by. It was a Monday, the day we get the girls for our week with them. Lisa texts my husband in the middle of day stating that Jake was cheating on her and that she was breaking up with him, was currently packing his things, etc. The next day comes, and their mother is starting to spiral on social media, specifically on her professional business page. She ends up laying it all out there for the world to see (via her social media stories). She mentions Jake cheating with real multiple girlfriends during their relationship, finding the underwear, finding out how he spent more money on vibrators, and nipple clamps for one of these women than he did “on me and my kids for Christmas and Mother’s Day combined” (direct quote, I have screenshots), going to couple’s therapy with Jake, his apparent sex addiction, him playing sex games on his computer and having cyber sex, and him owing her thousands in back rent on the home she owns. Mind you this was posted for the world on her public business social media pages. In a text between my husband and Lisa, she divulged more troubling details regarding the above and said that “I want you to know he will NEVER be around the children again. EVER. I am packing up his stuff and told his mom to come and get it as I do not want him here. Period.”
My husband had to help Lisa navigate this as this would obviously directly impact their daughters. As this was their mother’s business we offered to be there for the conversation with the girls for support for them but thought it was best if this news came directly from their mother as it was her relationship. The girls are quite young so I felt it wasn’t totally appropriate to divulge to our daughters that the reason Jake and Lisa broke up was because Jake cheated. My husband agreed, but Lisa pushed back and stated she consulted others and came to the conclusion that she would tell the girls Jake cheated.
So, their mother’s week comes, she tells the girls. We get them back the next week, my Husband asks the girls if they are alright, do they have any questions, etc.

The whole summer goes by. My husband gets a text this week from Lisa stating that she has an update regarding Jake. He asks what it is. She says that while they are not back together or anything, they are going on a date this weekend, and are back seeing a therapist as “many of the things I thought were going on, actually weren’t”. My husband confused, ask what she means, and she claims that the online games weren’t totally sexual in nature, he bought the vibrator/nipple clamps through an Amazon wishlist for an anonymous woman online (like that makes it any better). However Lisa seemed to gloss over him actually cheating in person, him buying explicit items whether he knew the person or not, and him bringing in another woman’s underwear to the house were his daughters live.
She mentioned that she heard his concerns, and that her and Jake are in a “wait and see” area at the moment, so they could end up back together or not.
I mentioned to my husband this is horrifying, my blood was boiling, etc. The fact that she went out of her way to tell her daughter’s Jake cheated, blasted him online, told my husband Jake will NEVER see the girls again. Then is now back tracking?? And is entertaining the idea of getting back together with him?? I told my husband that if she cared enough about her daughters’ well being that she would not even be entertaining this idea as potentially inviting him back in can and will be damaging to their psyche.

After all of that. We don’t know what to do. Do we let this play out? Let her ruin her trust with her daughters and us have to face the consequences of her telling the girls that cheating is unacceptable and then letting a cheater back in?? I have been so so sick about this all week. I just need advice.