Formal:
* Vous m'ignorez. (This is the most literal translation and the most formal.)
Informal:
* Tu m'ignores. (This is the informal version of the above, using the informal "tu".)
* Tu me fais l'ignore. (This translates to "you are giving me the cold shoulder.")
* Tu ne me parles pas. (This means "you are not talking to me.")
* Tu fais comme si je n'étais pas là. (This means "you are acting like I'm not here.")
More emotional:
* Tu me snobes. (This translates to "you are snubbing me.")
* Tu me délaisses. (This means "you are neglecting me.")
You can also choose a more specific phrase depending on the situation:
* Tu me fais la tête. (This means "you are giving me the silent treatment.")
* Tu refuses de me parler. (This means "you refuse to talk to me.")
The best way to choose the right phrase is to consider the context and your relationship with the person you are speaking to.