The title of the time-travel novel

The male protagonist called the female protagonist Nuannuan. The female protagonist knew poison and wore a human skin mask with a purple-red birthmark on her face. The male protagonist was a prince. The female protagonist had fetal poison in her body. It was the poison that her father had given her when her mother was pregnant. The female protagonist was also the person the High Priest wanted. In order to save the female protagonist, the male protagonist led the poison from the female protagonist to himself. A few years later, the male protagonist came back to look for the female protagonist. The female protagonist had already given birth to their child and was going to compete for the position of the leader of the martial arts world.