changed email but doesn't show up to login on ipad so I can't update apps

As long as you didn't create a new ID and merely changed the email address that you use for your Apple ID - go to Settings>iTunes and App Store. Tap your old ID and sign out. Then sign in with the changed ID.

If you created a new ID, you need to continue to use the old ID in order to update apps since purchases are always tied to the ID used to make the purchase.