Woods told reporters at the Players Championship Tuesday that the last few days since his announcement of the breakup have been "brutal."
"This three-day stretch is very tough. I haven't slept," he said.
The couple mutually parted and released the news via personal message on Woods' website Sunday.
"Lindsey and I have mutually decided to stop dating," the note read. "I have great admiration, respect and love for Lindsey and I'll always cherish our time together. She has been amazing with Sam and Charlie and my entire family."
The athletes blamed "hectic lives" for the split, admitting that spending time together was too difficult.