Internet (VDSL) connection sharing through wire/SFP with QoS and LAN security

I would like to share a VDSL internet connection with another spot near me (userB) through fiber.
UserB:

  1. must NOT have access to my (main) network/devices for security reasons.
  2. must NOT be able to drain internet bandwidth or I need a way to split/limit bandwidth use for userB
  3. should have a wireless access point in his place (an old/cheap router can be used as an access point for userB)
    Please recommend equipment and the appropriate configuration.
    Thank you in advanced!