I do not think you can use "until today" in your given situations in english. I actually understand why you think you could use it like that - there are constructions like this in my native language (which is lithuanian), but not in english. The first situation (He has been working with me until today) would mean "he" has stopped working today.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
When I want to describe an event that has happened to this day and can continue further on, can I use UNTIL TODAY ?