Anti Car theft circuit

Good day,

I just got be a new car after the last one was stolen,

Now i want to put in a relay on the fuel line, so that if some one tries to steal the car then they not gonna get it started no matter what they do.

Now i need some help with the simple circuit to control the coil side of the relay.

I am going to get a 12v relay,

Now what i want to do is, when u get into the car, you put your key into the ignition and then turn it to on, (this will enable the ignition power source in the car). Then i want to activate a button in my dash that then turns the relay on. But the complication that comes into play is that i dont want that button to have to be on the whole time. it must just be pressed and that then switches the relay on until it looses the ignition power source (ie car is turned off).

i have attached a simple paint drawing of what i want done:
please have a look at it,

So the relay is going to get its power from the ignition source so that if the car is off the relay will be off, and also to add another security feature. (u would have to hot wire the ignition and then as well figure out my button, vs just switching the button on).

And reason i want the switch ti just turn it on, is i dont want to be able to forget the switch on the whole time, and i am also maybe thinking of connecting the switch to the rear windows demister, so i just put it on for 1sec then off again and the relay will engage, or im thinking of attaching it to a button on the steering wheel radio remote.


So what kind of circuity (hope fully simple and basic) would i need to get this type of switch working, i dont know what to call it, cause its not really a state switch, it is kind of an only turn on switch, an it resets when it looses power?

Thanks

Dylan