Bremsstrahlung is not the creation of virtual particles, though it does involve a virtual photon. It is rather the radiation of (real) photons by electrons when they suddenly "decelerate" (i.e. collide with other charged particles). In fact the name "bremsstrahlung" means "braking radiation," if memory serves.

> when they suddenly "decelerate" (i.e. collide with other charged particles)

I think it'd be more accurate to say "interact" instead of "collide" – the electron could still be far away from the charged particle. More generally, bremsstrahlung also occurs when an electron's velocity vector (not necessarily its modulus) changes, i.e. when the electron changes direction, like in a synchroton.

> In fact the name "bremsstrahlung" means "braking radiation," if memory serves.

That's correct :)

Basically the change of momentum for the electron sheds some of energy used to accelerate it.

it is also important to note that due to experimental constraints and the nature of quantum mechanics different possible processes interfere with eachother.

eg: (a+b)^2 = a^2 + b^2 + 2ab

That 2ab is an interference term so a different process can get mixed in (quantum mechanically speaking). And we may not experimentally be able to disentangle it.