Dying Val Kilmer Buries The Hatchet With His Brother

Frail Val Kilmer can barely speak — but, in his final days, he's swallowed his pride to make amends with his estranged brother, RadarOnline.com can exclusively reveal.

Though he's refused to acknowledge the throat cancer that's killing him , the Top Gun star, who celebrated his 58th birthday Dec. 31, let bygones be bygones with sibling Mark Kilmer, 59, after decades of arguments over their differing beliefs.

Val, a devout follower of Christian Science, has used prayer instead of modern medicine to treat his disease, despite needing a tracheal tube to breathe in 2015.

Meanwhile, Mark, a clinical psychologist, has been forced to sit back and watch his sibling suffer.

"Mark is a well-regarded psychologist, so he doesn't see eye-to-eye with Val's Christian Science beliefs," a family source told RadarOnline.com. "It has caused a rift between them in the past, but now they're finally getting closer again."

The Kilmer insider added Mark must respect Val's choices of treatment, even if he "doesn't agree with them."

The two no longer discuss their religious disagreement with Val's death looming "because their relationship wasn't great for years," revealed the source.

"They've finally got things back on track just as Val is fading."

Val, whose weight plummeted to 89 pounds a year ago , also faces a declining bank account — which led him to sell memorabilia and signed photos through his personal website to survive.