It's a limiting belief that you have to take action. People who are telling you that are still stuck in their old world view and try to integrate LoA in it. That can't work and leads to confusion, as you see.

But it's also not true that you aren't allowed to contact your ex. If you can manage to align with what you want, it doesn't matter what action you take, it will work out. But for most people, it's easier to heal and to align without being in contact.