Texas Last Will And Testament Questions.?

Does my wife have to be the beneficiary of my Last Will and Testament? We both have had some bad experiences with family members attacking deceased relatives' beneficiaries. So I want to avoid leaving it to her, to save her from any scrutiny. I want to leave the duty to my cousin, whom I trust will communicate with her on everything anyway. But legally, can it be anyone other than her? And please PLEASE site sources so I can double check. The last thing I want is for it to be null and void due to a technicality. I couldn't find anything on the web. Thanks guys!