Hi there, welcome back, I am glad you found your way back. I am an alcoholic so I don't have any knowledge to share about drug withdrawals, but I think our brains work in similar ways. Isn't it incredible how time and time and time again we are shown that NO, we cannot drink, not even sip, NO we cannot just have a pill here and there or a sniff here and there or just one night here and there. We can't have any of that if we want to stay healthy and sober. One sip, one pill, one night almost always leads us right back to where we started.
I have a friend who has withdrawn from heroin several times. I had talked to him once about my problem with alcohol and asked him for tips or help. He said that when he was going through it he used meal times as a point of reference. He would say "I own't use until after lunch" and then he'd get to lunch and say "I won't' use until dinner" and then he'd get to dinner and then "I won't use until it is time for bed. And then he'd just go to bed instead of using and do it all over again the next day. You might be in a place where even smaller increments of time are better "I won't use for the next 5 minutes" etc.
Keep coming on here, seek out face to face support where you can. It is time to take a good, hard look at what you are missing in your recovery after 5 times in rehab. What can you do differently this time? What can you add? YOu can never have too many tools. Hang in there.