Texas, No Will- Wife or biological children?

A dear friend died a few months ago due to complications from an accident he had some time before, and did not leave a will. After his death, I didn't stay in touch much with his family as I was only just coming to know his biological son, who is 19 now. My friendship with his wife and stepchildren was on the decline due to her increasing unfriendliness towards me (my mother and I believed that she was having an affair with a boy about my age who lived with them, because neither of them had a job so they spent all day together and her unfriendliness did not begin until he and I started openly flirting), so much so that I stopped babysitting and making my once welcomed suprise visits, only coming over when my friend invited me.
So it all came as a surprise to me when I found a bulletin on MySpace by his biological son, speaking of how he'd gotten next to nothing after his father's passing. While I'm not very keen on what he seems to expect (reading between the lines, it seems somewhat like he's a little greedy), I know that his father was very important to him and, in my honest opinion, he deserved a little more than what he got (I think he should have gotten things like some of the vintage cowboy hats that were family heirlooms and the collection of knives that years were spent accumulating, because the hats were passed down son-to-son and the knives were verbally promised to be split amongst a handful of people, including his son).
I resolved to keep my nose out of it for a time because I was always taught to keep to myself out of the family matters of others when I have enough issues in my own. But I was spurned by anger tonight when I recieved a message from his wife, quoting his son's bulletin and not only making herself sound very hateful and greedy but also defacing her dead husband's name. Simply put, my friend was a good man and his memory deserves to be treated much better than she has been treating it while she trots about with the man that everyone was aware she was having an affair with before his death. (This affair was the reason his son moved out just before his death.)

Is there anything his son, being in his father's sole custody from age 16 to 18 and remaining in his home until shortly before his death, can do about reclaiming some of his property?

The the wife was running around is not legally relevant. Dad could have written a will to leave a modest share to wife (she is entitled to elect a share by law) and a decent share to his son...but he didn't do that and now the distribution is as TX law says it is to be.  Son is probably entitled to a decent share of Dads own property.   Verbal promises of a split do NOT count.

Son needs to look up the intestacy succession  "rules" for TX and sort out his approximate share and insist that adfministrator deliver same and if necessary seek the administration role to do just that.