The cream color looks like silk chiffon or georgette. Ah... Nicole says the same I now see. Possibly rayon. Is there any of that fabric in a hidden part of the dress? If so, you could use some of it to create a backing for the torn parts, to stabilize and camouflage them. If not, you can just buy some modern (or vintage) fabric of the same color and do the same. Alternately, you could simple end the design at the damaged part (evening it up to be symmetrical, of course). Tuck under the rough edges and make a new edge.
Bugle beads are easy enough to find if you want to add more, and if you want a better match, try to find vintage (hint: a vintage accessory or garment in unfixable/awful shape, purchased very inexpensively is a good source for replacement parts).
The question is whether it's worn and torn or actually shattering from dry-rot. If it's the latter, then fixing it will be very temporary fix. It will soon disintegrate, no matter what you do. Even so, if it's not expensive, and you can get a bit of use and joy from it for as long as it lasts, I'd say go ahead. I'm sure there are those here who'd disagree, but I believe that clothes are meant to be worn. Especially dresses!