Kevin Costner, Whitney Houston‘s co-star in The Bodyguard, will speak at her funeral Saturday.
Clive Davis, Aretha Franklin and Stevie Wonder will sing at the service, her rep has confirmed.
A family source tells PEOPLE, “Whitney’s family is devastated, but they’re getting through it.”
Adds the 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.