Las Malvinas son Argentinas
Sorry about your mum. To me her letter just sounded like you need to keep doing this, just to avoid family shame and embarrassment. In other words continue in the TRADITION of something even though it makes no sense anymore to YOU. Your feelings don't mean much in this equation.
Isn't this what they codemn the Catholic church members and many other church members for ;that they just follow in the traditions and not troof? But they have no problem with the hurt they cause new converts family members do they? They provide no simple dignified exit path for folks that no longer buy their dogma -- most reprehensible.
You deserve better than this, please take comfort in knowing that you are not alone and you will always find love, understanding and a sympathetic ear here. Perhaps you should consider sending her a letter back to defend your position, since it doesn't look like you have much to lose at this point.