It sounds like you are trying to unscrew a drain strainer from a tub or sink drain, and you are referring to one of those barbell shaped strainer wrenches. Frankly, I’m surprised you broke the wrench. Usually the strainer (usually made of brass, not copper) breaks, not the wrench. The strainer is usually tightened to the drainpipe with a “spud” nut. To loosen the strainer in most cases you need to hold the spud nut below the sink/tub with a spud wrench. If the setup is old, the strainer and the spud nut are probably corroded and will be hard to separate, especially if you are just working from above with the strainer wrench. You may try a judicious application of heat from a torch to loosen this corrosion, and you can also try spraying the fittings with WD40 or another lubricant. When these fail, as they frequently do on really stuck fittings, you’ll have to cut and/or chisel out the strainer and replace everything with new fittings.