As you've requested OP, I'm not offering advice, but perhaps more of an understanding of why obsessive behaviours happen. When there's understanding, obsessive behaviours can have less of a hold on you. I work ALOT with people with eating disorders and addictions, particularly women in their 40s/50s.
Agree with PPs that this is likely related to underlying anxiety. Obsessive behaviour and addictions can be coping mechanisms for the anxiety.
You mention that in your youth you suffered with an eating disorder, and food avoidance became an obsession. Anxiety can surface or become much stronger during times of hormone fluctuations i.e. puberty and menopause. Anxiety is further exacerbated by unwelcome and often distressing body changes during these times, which can trigger the unhealthy coping mechanisms. The harmful coping behaviours can take an even stronger hold when the obsessions are reinforced by advertising, Instagram, Tik Tok, your own high expectations of yourself etc. etc.
Some people breeze through these times of transition, but at the opposite end of the scale, menopause can be brutal for a lot of us.
Looking after your skin can be a positive thing, but like you said, not when it's taken to extremes and it affects your day to day living and enjoyment of life.
It's very difficult to "just get over it". That's like telling someone with a fear of spiders to hold a tarantula, or someone needing glasses to just focus a bit harder.
So I won't giving advice, other than to say go easy on yourself, be compassionate, be curious. The question is not why the addiction to anti ageing, but why the underlying anxiety. You hit the nail on the head about getting professional help.