Welcome to the forums
What settings are you playing with? What is the AIP? And how much game time is it taking to build up, say, 1000 ships outside your front door? It sounds like something is going on to accumulate them
that fast, but you may be expecting a different timeframe than most of us think in so I'm not sure.
Also, what bonus ships are available to you? What Fabricators are available? Any golems? Etc.
Anyway, one popular way to deal with threatballs (piles of AI ships camping you but not committing to an attack) is mobile tractor ships (the mkI Riot Starship is always available, though you may want a higher mark, and the Black Widow Golem is the master of this) sent through the wormhole, grab a bunch of AI ships, go right back through the wormhole, process them with
chipper-shredderturrets, rinse, repeat. If the Riots aren't likely to survive, send mkI fighters or other fodder to absorb the AI's alpha strike and clog up targeting lists, then send in the threat-thief units.
This is harder now that the AI tends to camp about 20,000 range out from wormholes (blame Faulty Logic for that, it was his suggestion), but you can probably get them to come closer to the wormhole by sending the fodder (mkI fighters, cheap stuff, etc) through and sitting on the wormhole (maybe a bit further from the wormhole than from the blob so they come close enough), and then send in the threat-thieves.
There are several bonus types that make threat-clearing relatively trivial in many cases: Zenith Autobombs, Neinzul Fireflies, and to a lesser extent the Youngling Nanoswarm or any other Youngling. The first two do significant aoe damage, but all of them are cheap enough to do something like this:
- build like 15 space docks directly next to the other side of the wormhole being camped. You may want to cover these with forcefields but often they're simply not going to be attacked during the operation
- stack as many engineers as you can spare next to the space docks. If you haven't unlocked engineer IIs, consider doing so.
- set all the space docks to FRD-move (V+right-click) to the target planet
- set all the space docks to loop-build
- set all the space docks to build one of each of the incredibly cheap units listed above that you have
- observe absurd ship quantities pour through the wormhole and attack the threatball (and anything else over there)
This can actually run your resources dry, so that could be an issue, but often you can do a simply ludicrous amount of damage to the threat on the other side for relatively little expense. At worst, the distraction of the stream of ships will make it easier for you to get your threat-thieves or simply your fleet in there to start killing the things.
As far as how you can get onto the offensive, there are some general tactics I could advise (a solid core of high-mark starships can work wonderfully as a raiding/stomping force) but we're really getting into territory where your specific game situation dictates what would work best, so feel free to post a save and some of us can take a look