Still, if something, It, is expanding, it must invade something. Its pure logic.
You are still comparing the expansion of the universe to an ordinary explosion, which involves outwards expansion.
Instead, the expansion of the universe occurs everywhere at once. The universe has no outwards expansion, and consequently there's no need to contemplate an 'outside'.
If distance, as we perceive and measure it, seem to increase...
When we talk of the expansion of the universe, we really mean the expansion of four-dimensional spacetime.
The way distance is measured in spacetime (the metric) is different from the way distance is measured on the surface of the Earth. This makes spacetime distance difficult to perceive. Points in spacetime are specified by four coordinates, one of which is cosmological time. The geometry of spacetime is weird in that the distance between points with constant coordinates increases with time rather than remaining constant.
Spacetime metrics is a lot of fun - not!