Hi, In high availablity mirroring if the connection between witness server and primary server is break off but if primary server is still up. The witness server will up mirror server. In this scenario both primary server and mirror server is up and this scenario is called as SPLITBRAIN.
Question1 : In this case the users are connected to primary? or mirror server?
Question2 : Once the connection between witness server and primary server break even primary server is up , are users connected to primery server or secondary server?
Your users will be connected to whichever server they are configured to access. If they have (for example) the "Failover Partner =" part in their connection strings, then if they have lost connection to the principal, they will try to connect to the mirror.
It kind of depends on the nature of the loss in connection between the principal, mirror and witness. If the primary is up on Site A, but the link is down between it and the mirror (and witness) on Site B, hence causing the scenario you have described, but the users are also at Site A, then they will still be on the principal.
If the users are at Site C, and there is no break in the link between C->A or C->B, they will probably still be connected to the principal.