Hello Redheadpanda.
I'm so sorry that despite you all talking about what had affected your relationship with your sons, nothing was really resolved and you are now estranged from them both.
There comes a time when you need to let them go; to get on with the lives they've chosen to live without you so you can find a way to live your life without them.
To say that isn't an easy thing to do is a gross understatement. It's so hard when you have a partner to share the pain; so much harder when you live alone, which is why it would be an idea to consider counselling.
We've been estranged from our youngest son and only GC for more than 13.5 years and with time, went from wanting things to be different to realising that they never will be and it was then that we began to heal and rebuild our lives.
In our experience and the experience of so many EP's I've read over the years, estrangement takes time to process and is more often than not a work in process, rather than a task that gets completed.
As well as considering counselling, you could write one more time to say that you love them, will always be 'here' if they need you but wont be contacting them again; this would be a good first step in letting go.
There is a life to be had after estrangement, it just isn't the one we thought we would have
.