updated 02/16/2012 AT 11:00 AM ET
•originally published 02/16/2012 AT 11:50 AM ET
Kevin Costner, the leading man who costarred with Whitney Houston in her greatest movie hit, The Bodyguard, is planning to speak at her funeral this weekend, a family source tells PEOPLE.
In addition, both Aretha Franklin and Stevie Wonder will sing at the service, and Houston’s record producer from the very beginning of her career, Clive Davis, will also speak, Whitney’s rep confirms.
According to the family source, “Whitney’s family is devastated, but they’re getting through it.”
In addition, says the family source, “Clive has been a complete rock for her family this entire time. He’s been with her since the beginning, and he’s been everything to them. They’re leaning on him for emotional support. He talks to them hourly, and he’s a very big part in planning her funeral. Clive has been a constant presence for them. They’re thanking God for Clive.”