Internal Back up link

Guys,

I need some insights from forum.

Don't know if you have done this setup up before, i attached the diagram of small network.

Normal traffic, VLAN10 go to link1, VLAN20  go to link20..all ok can go to internet. i did some PBR routing in the

L3 switch to pass to traffic to corresponding link. Gateway of VLAN is the SVI created in switch.

But one Requirement is to fail over the VLAN10 subnet to VLAN20 when the link 1 is down.

i can force the routing in switch to set the next hop of VLAN10 to be the link 2 when link 1 is down, but traffic is not passing through Firewall, it cant go to internet.

Any idea?