You’ve done brilliantly to get this far, really sorry to hear about your heart issues, that sounds very frightening.
You will get lots of support here but for more informed advice you might be better off going to Reddit and searching on the subreddits – these are individual forums focused on specific issues, with their own communities. There is the main subreddit for Methadone with 29,000 members, which comes up if you search ‘methadone’. There are other groups around opiate recovery, you just need to search within Reddit.
Good luck x