Acetone will remove the epoxy but be sure you have cleaned it and cleaned it AGAIN (even 3 -4 times). Is it plated or solid sterling silver? Are there solder joints near the area that needs to be soldered/fixed? If other joints are near, you will need to really protect these areas with heat shield or other heat barriers so they don’t come apart when making the repair. Hopefully silver solder was originally used (higher temp) and no attempt was made to lead solder the break before epoxy was tried. If lead solder was tried, far more problematic………….
This big of an item will need a torch much bigger than your jewelers torch, as the entire item will be heat sinking. The cement filling (most likely actually plaster/investment) will have to removed before working on it. The potential problems go on and on……….
It might not be “that bad” but without actually looking at it is difficult to tell. Also, is it a really good piece (solid cast sterling) or a cheaper silver plate. If the former and if it is old and really valuable, I would pass on the project. If not a very expensive item, I might work on it but I would not know, again, without examining it closely.