I have listened and discussed this decision with many of my family and close friends. My mind has told me that the time to retire is now. If you can't give 100 percent to rugby then you can't do it justice. This is a sad day, but I know that my time has come to an end as a player. My passion for the amazing game will never end or leave me however.
I do not know what lies ahead, but I feel the challenge of something different excites me more than another year of rugby.
I would like to thank everyone I have been involved with in the sport. I could not have achieved it without any of them. I have great memories and great friends that I will keep for the rest of my life. I leave knowing I have done everything in my power to be the best person and player I could have ever been. And finally, I thank my parents for all their support and help throughout my career.
The 37-year-old has played professionally since the mid-'90s. He geared up for eight different teams in Rugby Union before switching to Rugby League in 2010. He is one of the greatest Welsh rugby players of all time.
With the retirement of Thomas and Ben Cohen, the sport has lost two active opponents of homophobia. Cohen has dedicated his retired life to fighting that homophobia, and we know Thomas will do something of the same. We wish him all the luck in the world in whatever he chooses to do next.