Relapse is more of a process than the singular event of resuming use. It’s broken down into three stages:
Emotional
Mental
Physical
Emotional relapse is often the first stage of relapse, and it occurs before someone in recovery even begins to consider using again. The individual usually starts to experience negative emotional responses, such as anger, moodiness and anxious feelings. They also may begin to experience erratic eating and sleeping habits, and their desire for recovery often wanes due to a lack of using their support systems. These are the initial warning signs that a person in recovery could be entering the process of relapse, and it is important to recognize them as quickly as possible. This stage occurs before a person is even aware that they could be in danger of relapse, and intervening now before they enter mental relapse can prevent the issue from taking hold...

...Prompt action is the best way to address a relapse. The individual must recognize that a relapse, while not a failure, is a serious thing. Each relapse presents the potential to fall back into continuous abuse, which can lead to serious health problems and even death.

[link to americanaddictioncenters.org (secure)]

They took you on as a patient, knowing full well what was occurring. If they'd kick you to the curb rather then offering support...

You're experiencing a relapse - may be different from their "normal" patients, but much is similar.

May not know a lot of your situation, but if you ever want to chat about toxic mothers...