Scared of switching therapist

I'm having a hard time because I decided to change my therapist. I've been seeing them for maybe 5 years and they did help in some aspects. But lately it feels like a veil has lifted from my eyes - I realized that they have been behaving unprofessional at some instances.

Examples : very often coming late to sessions, not coming to one session because they forgot, giving kind of intrusive (?) advice on how to deal with some life problems (constantly telling me what to do) , not respecting my opinion about what i thought was ssri withdrawal symptoms etc, etc.

I kinda feel dumb for not doing this sooner , but i always went on like "I'm used to them, I can't explain everything again to a new person". Also it's almost like a toxic relationship thing where i didn't even realize some things until later. Also i sometimes feel like I'm overreacting.

But I've decided to switch therapists now. How do you start telling a new person everything that preceded those 5 years of therapy and what happened during therapy?

I've already decided I am not going to talk too much about my former therapist, or talk rude about them, because I don't think that would help anyone.

I might try to write down everything important as introduction, or something like that , any tips from those who switched their therapists?