Cleaning coffee mold from a cup I have gone on vacation for a month and forgot to clean my mug thay i left on the counter.
Im scared that after washing it out with soap and HOT water it isn't safe to drink out of. i boiled water in the kettle and let the boiled water sit in the mug for 10 minutes
This is a very special mug and i would hate to throw it away.
Is it safe??
It is safe.
If you clean it by either putting it in a dishwasher on a high temperature setting or sterilizing it with boiling water, you will be fine.
This is not specifically a question about coffee but about food safety in general, so usual measures apply:

Scrape off as much of the mold as possible
Put the dish into (boiling) hot water for at least 15min

It is a similar procedure to preparing glass jars for jam, you try to boil away as much bacteria and funghi as possible.