I would say it is likely the tail thing is a reaction to being kept inside.

As excessive grooming is a stress related condition and as this happen when she was restricted inside after 12 years of freedom to roam, it is probually related.

Luckily there are other solutions which give the cat limited outside access.

1) Walking her on an harness and leash.

2) Supervised garden visits or add fence toppers to restrict her to the garden and prevent the tom getting in.

3) Build Cat Run in your garden.

Good Luck

PS. Any chance on getting a local rescue group to trap and neuter the entire tom, then the problem would be solved.