I need to know how to make certain dnd character. oathbreaker paladin to death as backstory but chaotic good necromancer going forward.

When her wife was dying from incurable she pledged an oath to the God of death to keep her love from dying. killing all those who would dare defy the will of death (people seeking immortality, life extensions, liches, necromancers, undead, etc) this oath makes her classified as paladin. She comes home 1 day to find her wife dead. The God of death betrayed me. Takes preparations to preserve wife's body. In a rage she throws her shield onto the ground and shatters it with her sword effectively breaking her oath and swears vengeance upon the God of death. Raising those she killed in death's name and recruiting them to her army against death. Healing those meant to die. Becoming a lich. And most importantly restoring her loved ones soul and body from the God itself.

I want to introduce this character to a party initially as a villain that the townsfolk tell the party about someone disturbing the graveyard. They come to discover me raising someone who I killed in service of death. After the conflict I explained everything and we agree to join sides as we grow stronger, even enough to challenge the gods themselves

I want her to look like she used to be a paladin but is now clearly a necromancer weilding a sword and dressed in armor, no helmet though. If it's essential for me to have a necromancer wand I'll attach it to the sword in essence the sword is also a wand