EXCLUSIVE

Former "Big Brother" star Christmas Abbott struck a pretty sweet deal in her criminal mischief case -- she has a hefty bill to pay ... but won't spend any time behind bars.

Abbott -- who finished third on season 19 of 'BB' back in 2017 -- has been sentenced to 12 months probation and 25 hours of community service for a violent altercation with her baby daddy's girlfriend last year.

As we reported ... Christmas was arrested in November for the August 2018 incident, in which she drove to a Tampa gym to confront the woman and ended up flying off the handle and ramming into her car in the parking lot.

The only reason Abbott wasn't hauled in on the spot ... she was 8 months pregnant at the time. She turned herself after she gave birth to a son in October.