I would pass the EMAILs/Whasaps to both Easyjet's and BA's human resources (or whatever it's called this week) explaining that some former colleagues are attempting to pressurise you into doing something you aren't going to do.
100% this.
DG you need to remember that we live in a time where these two most definitely could make trouble for you, if only by alleging you did/said something to hurt their feelings, whether you did
or not. A couple of complaints to BA about your previous bullying or homo/trans/anything phobic comments or actions whilst on the shop floor and it will no doubt mean a lot of ar$e ache for you to deal with. Proof and/or evidence aren't required in 2023 and BA is a most woke employer and will want to be seen as such.
You'd be far better off getting your retaliation in first, through the proper (HR) channels obviously. Explain to both companies (but most importantly your current one) what's gone on and provide screenshots. It will head off any potential problems further down the track.