Thinking once again somehow of how important it is to me that when Wei Wuxian came back to life in Mo Xuanyu's body, the only two people who recognised him were Lan Wangji and Jiang Cheng.

Nothing is more proof of the fact that Jiang Cheng cared deeply for Wei Wuxian. Yes, he was hurt and there was anger but the fact that he held onto his rage and grief for years doesn't read to me as, "he hated Wei Wuxian so much he never forgave him for anything." Rather it reads as anger being the manifestation of Jiang Cheng's grief around losing his brother and closest confidant.