It is an illness because it is a personality change, which is part of the definition of some mental illnesses, especially bipolar. It is very common to overextend yourself on every avenue in mania: spending, sex, drinking, partying, socializing, talking a mile a minute, doing projects (which you often start half a dozen and never finish), and so on. Because it's part of a disorder, you do have to take precautions, and be thankful that someone else has your credit cards so you don't get yourself into more trouble. I had to give my cards to my partner last summer. But I kept my debit card just for necessities, knowing I couldn't go past what I had in the bank. Don't beat up on yourself for having the urges. Maybe use your energy to go through what you already have in the closet and reorganize it. You'll find clothes and things you'd forgotten about and it will seem like you just went shopping. At least that's what happened to me when I did it last summer. Just a thought. Feel free to ignore if it sounds dumb.