My Ex's Lie Ruined My Life & My Parents Chose to Believe Her and Abandoned Me. Now They Want Back in My Life After Learning They Were Wrong. #redditstories #redditupdate #askreddit
The OP's ex girlfriend's actions cost him everything and the distrust from his parents forced him to leave and start over elsewhere and that's a small reality that can't be ignored ever, so he has a right to go NC with both his parents and his ex girlfriend in the long run plus he's engaged and ready to start a family in the near future and that can't be affected for any reason whatsoever period.
Demand an apology, and if they don't tell them to go f themselves; go NC. Rachel needs to understand OP's feelings and not discard his actions to leave his family once and for all to start a new one with her. It is also good to see OP and his sister reconnecting. They favored the ex more than their own child.
When you hear your kid, or anyone you know/love, has done something so completely out of character for them, talk to them. Don't just jump to conclusions.