It was a really rough time after I got the cPTSD diagnosis because it really changed the context of my life. So my brain, being so very helpful, decided to do a 24/7 stream of my past for reconciliation. Probably not a unique experience so here’s tips I could have used earlier on:

mindfulness practice is paramount so that you’re not just like dissociating into oblivion or getting consumed by flashbacks. James Gordon’s “The Transformation” (also printed as “Transforming Trauma”) is pretty solid on the mindfulness stuff, though some of it needs to be taken with like a fistful of salt.
sleep hygiene is everything since without it, symptoms are worse and you’re less equipped to cope. Do not be afraid to get psychiatric help if nothing is working. The last thing you want is to be in urgent care after being awake for four days straight.
get on some anxiety medication. Helps with the sleep and with having more mental space when flashbacks hit
weekly therapy
lean on supportive humans in your life. DBT might help stand in if you don’t have those, but you need to be careful that it’s not a group dominated by cluster B personality disorders (I.e. people like your abuser(s))
schedule time for soothing activities that you enjoy
exercise. Doesn’t have to be extreme, but like try and at least walk for half an hour a day.

Tl;dr - sleep, mindfulness, therapist, psychiatrist, support of loved ones, self-care, exercise