Ladies, please feel free to improvise and tailor to suit you as I do for myself, now and then. It doesn't have to be an imaginary letter written on notepaper but could be an imaginary digital message, telephone call or face-to-face conversation taking place in the location of your choice. Make it work for you so that you can safely experiment with wording and tone and give voice, with feeling, to whatever you want, hope or need to read/hear/say.
For example, Starlady, "Mum, I fired yet another accusation at you by glibly assuming that you were in denial. I may even have lost my temper and shouted this at you. This was wrong and foolish of me as (a) I'm not a mindreader able to peer into your or anyone's mind and identify its defence mechanisms with cast iron certainty (b) judgemental accusations levelled against us, shot from the hip and with anger attached, are likely to make most of us on the receiving end feel defensive and therefore less likely to listen in order to think about them carefully and try to reach a better understanding. Of course I would be exactly like this myself if you suddenly fired accusations at me in an emotionally uptight/hostile/superior/self-righteous/rude/disrespectful way. I understand that you must have been seething - and still are angry with me - because I tried to force you to accept what I saw as 'the truth'. The version of me who is writing this/sitting with you today knows that just because I latch onto an idea and invest it with deep meaning does not of itself make that idea wholly and categorically true at that time/for all time. It may not even be partly true. For example, magicians often use suggestion in their tricks. Is the woman really sawn in half or levitating in the air? Flat Earthers insist that the earth is, well, flat. Why, I wonder, do they need or want to believe that so badly?
Why did I level these accusations at you and charge you with being "in denial"? I don't really know the answers for sure, Mum, but will do my best here to search my memory and try to explain. Is it ok with you if I try to do that? It may be the case that I will need to make several attempts. If so, can you please bear with me?"
Police launch an investigation into Ann Widdacombe death
I think that both you and your mother have benefited from the periods in which you've estranged yourself from her.
because despite having to deal with a difficult and at times upsetting relationship with your mum, you have done your best to preserve as much of it as you can.