When you are muddling at home always use a tin. Professional bartenders use a special heat tempered glass that is more durable than glassware found in the home. When muddling in a glass always take great care.
Seek out mixing glasses that are heat tempered and have a “T” on the bottom of the glass.
Never muddle in any other glass. Use at your own risk. For fail safe muddling the use of a metal mixing tin is recommended.