To NAT or to route

I think I have a NAT issue but then it could be routing

Scenario: I have a L2L VPN with an outside vendor in which I must double NAT a single host. (the only host that needs to communicate with the opposing network)

my inside host = 192.168.0.57/24

my inside host's NATed IP = 192.168.251.130

Cisco ASA 5505 8.2.5

The tunnel is up, stable, and the single host can connect to the opposing hosts fine, but cannot access the internet

Can someone point me in the right direction? please? help?

Thank you in advance

Running Config is attached