“Bailing” in this context means to quit, to leave, or to be absent. So, the sentence means “I’m sorry that I have not been around to be with you [or help you] until just now.” “Bail” can have a neutral connotation or a negative one. Neutral example: “It’s getting late. I’ve gotta bail.” Negative connotation: “What an asshole. He bailed on us when we needed him the most.”

"Bailing" is colloquial for quitting abruptly. It comes from "bailing out", as from an airplane that has been disabled.

Bailing someone has different meanings: To break a date with someone. To tease someone. To speak spitefully against someone. To criticize someone.