You need to pop the gel coat flakes off, rough the area up slightly w/ 80 grit and fill with thickened epoxy (which all JB Weld is). I'd probably use WEST epoxy with 407 Fumed Silica just because I have it and the color is not as objectionable (JB Weld is black). Then re-drill the hole.
Unusual to have the bolt break. Usually it's the tang.
Its was the bolt that failed i have the tang still attached to the bridle wire. Whether the bolt came unscrewed or broke I don't know; however, I'm pretty sure it was the original bolt, as I didn't replace it when I got the boat. All the shrouds have been replaced should i replace the anchor's and pin's as well?