A pile of used calling cards is pretty useless, because you have no idea who was called. If you could get call history from the calling card company, that would be good, but I doubt that you can.
I don't think it matters all that much whose name is on the phone bill. If you can show that you lived at the address on the phone bill and the bill shows that someone at that address has been constantly calling your spouse/partner, that should be good enough. Who would be making all those calls if it wasn't you?