tad, good advice here. Ask yourself some questions. What would be the result of sending the letter?

As far as I can see reconnection with the ex spouse [even if there has been no formal divorce] is tentative, slow and faltering, with many back and forths. They do not seem to wake up one morning and think 'OMG I have made a terrible mistake, and will make full amends immediately'

They appear to edge/inch out on most cases, if they do it at all. Beware false dawns [i have seen a lot of these] Reconnection, if it happens seems to be very slow, and it is a long time down the line. The short MLC is the exception. In the experience of people I know, some of whom no longer post, the LBS is not at all sure that they want the damaged goods in their lives.