Does the nipple get cut off during a mastectomy if it dies?

Sorry to learn of your healing difficulties. It is best to discuss your concerns with your plastic surgeon. In general, the outcome from breast reconstruction depends on many factors not the lead of which is the blood supply to the breast skin, including the nipple, upon completion of the mastectomy. Your plastic surgeon and breast surgeon together decide on the best course of action during surgery after the mastectomy is complete, but sometimes there are indeed healing complications. As a rule, if the blood supply is insufficient, the area of skin or underlying tissue will go on to heal poorly and either require surgical removal ("debridement"), or will heal over time with good wound healing. It is best to follow up with your surgeon. If you feel that a second opinion is required, please consult with a board certified plastic surgeon experienced in breast reconstruction. Best of luck to you. 

When the breast tissue is taken away, 50% of the blood supply that comes from the tissue is now gone and the skin and nipple must rely on blood traveling through the rest of the skin for nutrients. If the incision is close to the nippl are areola. This puts a lot of stress on this tissue during surgery- like putting a rubber and around your finger. If the tissue is stressed and has decreased blood supply, the tissue can suffer and die, but the closest tissue that is still living and heal the area. If the nipple turned black, the skin can die, but the underlying tissue that hasn't died will be raw and bleed when the dead tissue sloughs off. If the damage is minimal, it may completely heal as if nothing ever happened. If it there is a lot of damage to the blood vessels, there may be nothing to save and the whole area may need to be removed. Having a skilled surgeon who can remove dangerous tissue while preserving healthy fat and blood supply is an important part in preventing dead tissue and nipples when a mastectomy is performed. 

I am so sorry to hear of your post mastectomy nipple issue. If the blood supply is compromised the nipple may completely die  or only a portion may necrose. If the nipple is not completely dead, but ischemic (lacking adequate blood supply), it may be salvageable. Applying blood vessel dilating creams and antibiotics, keeping the breast warm and time may improve things. Hyperbaric oxygen is controversial, but may improve blood supply to a compromised nipple which is not completely dead. If the nipple is partially dead, that tissue must be removed to prevent infection, but if part of the nipple is viable (alive) it should be preserved and watched carefully. It may be preserved. IF the nipple dies and cannot be saved, it must be removed. Once the wound heals, an new nipple can be reconstructed using adjacent skin to make it 3 dimensional then tattooed an appropriate color. Some tattoo artists are so good that the tattoo alone looks 3 dimensional and very natural.