A lot of good stuff has been said but I would point out both that Simon Tolkien was publicising his first novel when these stories emerged ( and that sensation sells.) and that the world has changed a lot in the past forty years, fathers are generally much more involved with their children and the needs of children of separated parents are better understood. So even if there is an element of truth it wouldn't make CT particularly monstrous by the standards of the time. Even in families that stay together it is not unusual for a child to have a better relationship with one parent than another ..it certainly was the case in mine..
I am just now reading the letters and from them, you can glean the deep love Tolkien had for all his family. If you look at the donations of the Tolkien Trust you can see the kind of people the family are by the wide range of humanitarian causes they put the money from the estate to. And having recently had the pleasure of receiving a charming personal reply to a communication that demanded no response at all, from Adam Tolkien I can second Lalwende's comments. But I did not need that or a lawyers statement to know that the blog was ludicrous and libellous and guess the Simon Tolkien quotes "spun"
... frankly it would not be saying a lot for JRRT's judgement if it were even half true.
As for access ..I am sure we would all love to get our claws on everything. It isn't possible but HoME is enoughfor most ..and I believe that some of the Trust money is going on making some of the archive available in a more accessible form.