I would recommend you remove the nvidia drivers and retry this. Installing Nvidia drivers with optimius support is tricky. You will need bumblebee, you could still use only the nvidia card (or only the intel one) without bumbleebee.
update-alternatives --config glx
Which should let you select between the two cards. When you select the nvidia card you can use nvidia-xconfig to automatically set up your xorg.conf. nvidia-xconfig can be downloaded from the repository
Removing Nvidia Drivers:
If you installed the nvidia drivers from the official repositories, what you need to do is:
apt-get autoremove nvidia*
If you installed the drivers by manually downloading them from the nVidia website, then what you will want to do is run
Your next step will be to revert any changes made to your xorg.conf configuration file. By default it is empty on Jessie (unless im mistaken).
Now; when installing the nVidia drivers the built in nouveau drivers are disabled by the addition of a file which blacklists. To re-enable nouveau you will have to remove a file that was generated by the nVidia installation. One of the files in /etc/modprobe will have a line that reads blacklist nouveau. Delete that line, save the file and then run the command
Finall just reinstall the nouveau drivers to make sure nvidia has not overwritten anything
aptitude install xserver-xorg-video-nouveau and xserver-xorg-video-intel
This should revert what the nVidia installation might have done.