Melting glass

Trying to shape glass from broken bottles into a heart with a differently collected glass border and was wondering if I could do it in the foundry? I would flatten it by heating then place the other pieces of glass on top but don’t won’t it to fuse to the fire brick what should I put under it? Can i cut the red hot glass with some big wire cutters? What temp would make the glass malleable but not liquid and how can I make it keep the shape? If anyone has experience in melting or heating glass please let me know how I can make this.