Employment advice- return of a (previously) mean boss

Hello all, I wondered if anyone has been in a similar situation or can offer advice. I work in publishing advertising sales and have done so for about 15 years. About 12 years ago I worked at a company where the policy was very corporate. I had a boss for while who I complained about to HR and then in revenge disciplinary action against me, to cut long story short this resulted in not only a year of much misery for me in the workplace, but also bonuses I had worked hard to earn being stopped many times(to the tune of a few £000s). Any way I left that company 10 years ago and now the old boss I had the grievance with has just been hired at my company now and in the role where she is my boss again! I appreciate it was a long time ago and I am much better in my role now and feel much safer now as I am quite highly thought of in my company plus we will both be in a much better less 'toxic' environment but it is still a bit concerning. Any advice?