In my opinion, the Sussexes would have been much better off to bring the lawsuit without publishing Harry's highly emotional letter. The merits of the lawsuit stand on their own, and the details about the letter Meghan wrote, Meghan's father, and their relationship are already likely to result in much more attention, discussion, press coverage, and muck raking than anyone would want to have to deal with. Harry's letter just adds more grist to the mill, and results in lots of unnecessary speculation, as we have seen on this thread.
The capper is that it is likely to fuel even more critical and speculative coverage in the press, and the timing altered the trajectory of the overall positive coverage of the SA tour in a way that pretty effectively killed the momentum the last day and a half of the tour. The letter and its publication is making me question Harry's judgment a bit.
edited for clarity