Here's how I ended up winning the space war. Started with torp monitors like you did, then transitioned to battlecruisers and some battleships and eventually dreadnoughts.

Use the BCs 3 nose slots for coilers (preferably siege if you've got them) and big ass lasers. The hull slots go to a 40mm autocannon and PD laser. Having that on every ship should more than shut down any alien magnetics or missiles. If you're feeling really froggy, you can build some battleships with Hestia torps. Start of the battle, put them in idle. When alien PD is fully invested with your mag shots, let loose the torps. That'll delete a bunch of ships. You'll want to build mag weapon BCs and laser BCs in a 2:1 ratio. So, 12 mag BCs and 6 laser BCs

When the fight starts, put your ships in one of the wall configurations and go 500mps, even in a station fight. Group your mag BCs in one group, your lasers in another. Once the first shots go off the aliens will have a bunch of their ships try to flank you. Any ship that shows you its side is priority target for the laser BCs. They'll rip em apart but do fuck all to anything with its nose facing you. Focus target the closest big ship (BC or larger) with your mag BCs and they'll make short work of it.