@Windowscratch
I've had similar this year with a younger colleague (shes 30 ish I'm 50 ish), she moved roles within our team and I moved into her old role.
I actually have 30+ yrs experience in our industry.
She has taken to making the transition as difficult as possible, withholding information, talking over me in meetings about my projects that she no longer has involvement in etc.
Definitely doesn't want me to succeed to the point of wanting me to fail, possibly as she doesn't want me to outshine her, I've actually discovered several major failings from when she was in my role.
When this hasn't worked, she has changed tack to bad mouthing me, it's so true that when people can't control you they try to control the narrative around you.
All through this I've not risen to the bait and senior management have seen through what she's been doing and she has been taken to task, talk about shooting yourself in the foot!
How I handled the situation was to remove myself physically and emotionally (we used to be friends, nights out, regular visits to each others homes, I supported her through some family issues)
I refuse to get into a tit for tat scenario, I actually look like the sensible, professional that I am.
I work hard, I send regular project updates to my line manager and say nothing negative about her.
Funny thing is she's failing at her new role (this gives me no pleasure btw) but she's shown what she's really like and the whole team and management can see it, I actually feel a bit sorry for her.
Hopefully you may be able to take some tips from my tale of woe