Internet Queries Through Specific Network Card

Good Days Guys

I have a Problem On my hands i need help with.

i am an admin for a network that spans tow branches. A & B
The Main Branch (A) is self sufficient :
Branch (A) And (B) are connected via a 3Mb Fiber Pipe. which is used by Branch(B)
to access software stored on a server at branch (A).

Server 2008 R2(main AD Server)
Active directory,File Services,DNS,Sites And Services,

Branch (B)
Server 2008 R2
2 Network Cards - On Connected to the LAN and The Other IS the ISP.

Active directory(sync to Branch A),File Services,DNS,Sites And Services,
Routing and Remote Access.

The Problem is that branch (A) Provides internet to Branch (b)
Branch (B) Has its own internet connection and does not want to depend on Branch(A)
for internet access. This will cut down on the traffic coming through the 3MB Fiber Link.

I use internet sharing through routing and remote...