have to disagree with cogito
i think counselling would help you because as they always say you cant change them but you can change the way you feel about them, counselling might help to put them into perspective.
i dont have this prob with my paretns but with my dh parents - she is narasicist and fil is enabler.
when i met dh he was in very expensive therapy learning how to deal with them...and helping him being un tangled from thier mess....
whilst he still has lots of issues with them, as it doesnt switch off over night i have noticed - that i struggle to deal with thier brutality over the years- but i cant afford the expensive therapy! i wish i could.
we had one relate session however that was enourmoulsy helpful and if we could have afforded would have def gone back for more.
it helped us - put us first not them, and unite us more as a family unit that should be protected.
we have severly limited contact and dh is much much better at not bieng bullied by them - his dad bullying on behalf of mother who cries and uses emotional black mail all the time.
infact his therapist helped him see the cyrying as a tool to get her way - which gave him the realisation and strgentgh to not cow down to it.
if i may say if they have treated you without due ..whatever in the first place they are unlikley to repsond to a letter or email as they just dont get it - or wont it - there are none so blind as those who refuse to see....
i very naively wrote my much older sister a letter about me being keen to put the past behind us and forge a relationship - i really opened up in the letter....and when i went to visit her ( she lived abroad) hoping to start afresh etc....i found her then partner waiving my letter round all the locals at a pub he ran, laughing at me and my letter!!!!
i was totally ridiculed. but lookingback what did i expect? she had never treated me well - why would one letter from me change that? she didnt have it in her.
over the years i did try again, until the last time last year when i realised FINALLY....she will never ever be able to give me what i want - she doesnt have it in her!
there is usually one side who is the willow - flexible - willing to embrace - reasonable and one side that is rigid and un moving...and un reasonable.