You are obsessing and looking for an excuse to make contact and relieve your pain.
So let's assume that W has doubts about OW. Do you think reaching out to her is going to going to make her miss you? Or does it relieve her so she knows she has more time to decide?
Your W needs to feel like she is losing you. She won't feel that way by you talking, texting etc.
Telling her she is going to lose you, doesn't carry as much weight as simply going NC.
People who are moving on, dont warn the other person. They simply stop communicating - they don't care anymore. This is what you need to project.
Your W hasn't forgotten about you, I can assure you.
You've planted the seeds in her mind by going NC. Allow them time to grow.