Hi palmtree, welcome to SR and welcome back from active addiction. I was seriously addicted to pills, too, oxy was my main DOC (drug of choice),at the end I was on insane amounts and snorting and injecting them. I also did illegal and shameful things while using.
I am the kind of person who gets lost in shame and guilt but I am working on it. Hoping to not live in the "Guilt Palace" (as I like to call it) one day. One way I do find these feelings helpful, though, is when I have cravings. I play the whole picture of using out in my mind, including my feelings of shame, remorse, regret, guilt and it helps a lot. It's so easy to remember only the high and it's important to remember the full picture. Maybe you can use your feelings this way instead of using them against yourself.
I am taking suboxone as well and it has changed and saved my life. I also attend outpatient counseling, group, and am on SR whenever I can. Also read and journal. I'm still looking for other ways to help my sobriety though I live in a rural area and it's hard to find a lot of choices. I keep looking though.
Take care and keep going strong!