My suspicions were true: my now ex gf was talking with Chad (sort of, guy was semi BP in her conversations) behind my back. I spied on her Whatsapp, and there was absolute proof that she wants a relationship with this guy. Broke up with her without telling her what I knew.

But we have a loooong class together, and we will inevitably see each other. How do I overcome my oneitis for her? Thanks.