not acknowledging your presence. You feel invalidated.
Validate yourself, rather than expecting others to validate you. If you have a need for validation from others, you are at a disadvantage.
You cannot control what others do, so don't let others' behavior distract you. They behave in certain way because who they are, not because who you are.
If this was not the first time you and him met, throwing you off balance might be the intended effect.