I am almost 12 weeks post op tummy tuck, when do the incisions stop hurting?

Thank you for your question and congratulations on your surgery. Without examining you in person it's difficult to say why your incision is sore. Your description of bits of pus coming from the incision suggest that there may be some sutures that are "spitting." This occurs when the  absorbable sutures placed under the skin make their way to the skin surface before the body can absorb the suture. It can cause a small amount of pus and a tiny open area at the incision line. This may be the cause of your soreness. The treatment of a spitting suture is keeping the area properly cleaned, covering with a Band-Aid, and ideally removing the suture from the tiny opening in the skin. With proper treatment, the tiny hole should heal in one to two days. Whenever there are concerned, never hesitate to contact your surgeon for specific advice. They are your best resource when questions arise.

Most patients have stopped hurting at 12 weeks.  I am sorry that you are still having trouble, but the draining areas will delay the recovery.  The good news is that the 'spitting' sutures largely subside in the first 2-3 months, so you are likely almost there.  

Everyone is different is the short answer. Certainly  scars that that are in the hair  bearing region above the mons pubis can I have delayed healing and ingrown hair. As well many dissolvable sutures will simply express themselves over time rather than dissolve . This is simply just different for every patient and not abnormal.