Here is how you accomplish a virtual MT instance acting as gateway for a bunch of VMs.
Add 2 vSwitches.
The first one is called "WAN" and you add the physical NIC to that switch.
The second is called "LAN" and has no physical interfaces.
Configure your virtual MT with 2 E1000 NICs, one connected to WAN and one to LAN. Boot the virtual MT and configure its interfaces. In the following example I will assume the MT interface "Ether1" is connected to the WAN and "Ether2" is in LAN.
Configure Ether1 with 192.168.1.151/24 (or another open address).
I assume the physical MT device acts as gateway for the network and has address 192.168.1.1. Therefore your setup the default gateway on the virtual MT as 192.168.1.1.
Next we configure Ether2 with IP: 192.168.2.1/24.
You are now done configuring the virtual MT.
Now change the "Virtual Domain Controller" and "Virtual Linux Server" so their NICs are bound to the "LAN" vSwitch.
Last you add a static route on the physical MT:
DST Address: 192.168.2.0/24
Gateway: 192.168.1.151 (or what ever open address you assigned Ether1 on the virtual MT)
That's it now you can reach the VM hosts and they can reach the internet.
You question does not address this, but i would like to save you the frustration in case you want to setup a DHCP server on Ether2. It will not work unless you change the "LAN" vSwitch to allow promiscuous mode. That can be done in the vSwitch config.