I was sailing on Saturday in about 15 mph winds when I noticed that my forestay cable was not connected and that the mast was being held up entirely by the jib sail!!!

I couldn't get the cable fastened while we were on the water so needless to say, we headed straight in (zig zagging up wind for an interminable ride, every minute expecting the jib to tear and the mast to come down). Ultimately, the horseshoe shaped fitting which fastens the sail and cable to the furler was bent, the screw was a bit bent, and it took quite a lot of time and some pliers to connect the forestay again.
Has this ever happened to any one and what causes this? Is there a way to secure the little screw so that it does not come out?
Also, now that the horshoe fitting is bent, can I still use it or should I replace the part?
Any advice would be appreciated.