Denial and shame aren't good for your health, and they can really interfere with your ability to commit to treatment. Some people start treatment because they're "supposed to" or because their doctors think they should, not because they choose to do it as an act of self-preservation. They do it grudgingly, like a chore you do because someone asked you nicely to do but you really can't wait to finish -- and, honestly, you never got why it was important to do, anyway.
Let's face it: Going on treatment means acknowledging, every day, "I have HIV." What happens on the days you don't much want to acknowledge that -- to yourself or to others around you? A treatment regimen is dangerous place to play out resentments.