Dear Isis,
Many children who have suffered violence have memory gaps... some lose detail, some blank out entire months or years. it is a defense mechanism against trauma and can happen in adulthood for acute events as well.
Clearly it is bothering you as you find yourself wanting to write about it - perhaps it is starting to creep up on you now for any of a number of reasons.... triggers you may not be aware of, or conversely an emergent desire for personal growth... could be anything.
With everything you already have to deal with i can't say if going full throttle into specific therapy is the best thing here ... yes there is a trade-off. you may ultimately gain even more than you bargained for... but to get there you may face more pain than you bargained for. only you can decide.
one thing i could suggest is, go one step further with your therapist: discuss the "to delve or to leave buried" question. spend a session on that alone. perhaps she can provide some general information as to what "delving" might entail therapy-wise, and help you gain insight on what you want to do.
~ waves ~