i'm sorry - no real advice to offer, but i can tell you you are not alone.
You asked about where to begin? i think you've taken two huge steps, in finding the courage to confide in someone and in reaching out here.
i also think finding a therapist - when you're ready to - is a good idea. Local crisis centers and hospitals can help in finding them. Not sure what the links are offhand, but you can search on the internet also. i would be lost without mine. As supportive as my husband is, there are things only my therapist knows.
You're used to dealing with things alone? You don't have to. A therapist (counsellor, whatever) can help lighten the load.
As for memories & flashbacks, the only thing i can offer is my own experience. i spend a lot of time just grounding myself - concentrating on my breathing; being aware of my surroundings, reminding myself that i am safe here and that the abuse is over, it's not happening now; sometimes just curling up & hugging a pillow helps. It gives me something solid to hold onto and provides a sort of barrier between me and the body memories. Sometimes taking a shower or bath helps: i can picture the sensations rolling off of me with the water.
just a few ideas i've found helpful over the years...
please remember you're not alone, and take care.

Sassy