I used my girlfriend's debit card five times at $100 a pop. How much jail time am I looking at?

You certainly face multiple counts of petit larceny which assuming the thefts occurred on different dates you could face up to two years in jail if given the maximum consecutive time. And if you took the debit card without permission then you could face up to four years jail on an E felony for Grand Larceny in the Fourth Degree. You should never post admissions of guilt on a public forum such as this, as they may be used against you to prove your guilt. Contact the lawyer who represents you on your other case and let him know of the impending Violation.

You face having your probation revoked as well as numerous charges. The theft would be a misdemeanor but using the debit card could change it to a felony (at least in Wisconsin)