@marriagehelpplease
You are well rid of team members like that. They are never going to hold their hands up to any wrong doing and will lie their heads off to anyone who will listen. You will always feel like you did something wrong even though you probably didn't or it was no where near as bad as they said. She is making this sound worse to upset you, don't give her that level of control over you. She would love that you are still upset about this.
Lying team members is another part of management, it sounds like you keep records anyway. Don't allow their lie to live otherwise you've just let them railroad you. You never get thanks for giving in.
If any of your colleagues get mentionitis again, just remind them they only have half the story and as it was a staff member, past or present, it is tied up with confidentiality, you cannot talk about it. This is not a lie, unless they are your manager or HR, it is nothing to do with them.
You do have to take it on the chin unfortunately, it's part of the role. Sometimes you just have to acknowledge a bad experience you are having or have had and then clear it out of your head. If you are dwelling on it, just vow to recognise the signs earlier and do something different next time. Once you get into that habit the pull to dwell starts to disappear. No one is perfect and no one can do the right thing all of the time and that will be what comes into your head when you start to think about it. I made a mistake, this is a great opportunity to improve.
If I may offer a point, any file staff shouldn't be accessing, lock them down with a password for the files or folders, give those who need access the passwords and ensure that anyone asking for the password is not to be given it unless you personally say so. There are too many open files in some offices that people delve into as and when they want.
Final note about we button pushers from a self confessed one. Do stop the button pushing when it starts, something light like, "keep that thought and we'll discuss it later". If they are non-verbally button pushing (huff and puff, smirk, eye roll, mumbling, yawning etc.), then book in a meeting outside of the others team members hearing.
Once you are ready have a quiet discussion about it with the team member. Ask them why they did that or why they asked the question/made the statement they did. Listen to their answer carefully without interuption, if you need reflection time, tell them you will take it on board and get back to them. Provide feedback, not how you personally felt but how it affects the team, derails the meeting, and how you want to proceed from now on. Write out a plan and ask the team member to confirm it.
The non-verbal button pushing is the really tricky one but still worth a discussion. It could be that you always do something prior to the distraction that that could be changed, or you let one team member talk more than the others or allow them to interrupt, or the meetings go on too long. However you will get the occasional dunno or don't care team member, it is at this point you may have to speak with your manager and HR for support in a way forward.
Not all button pushing is bad, some of it averts issues, down to more experience, someone who thinks differently, or is trying to grow within their role and is really requesting more information. Understanding why they are button pushing is really helpful to you as a manager and them as a staff member and can help your whole team grow even if they button push for less than reasonable reasons.
Please don't worry any further about this staff member, she will eat into your self esteem and no one needs that. She is yesterdays news and just because others still don;t think so then maybe their need reminding that it is not up for discussion.