Staying calm when getting swarmed by knights

I'm a noob player, thanks to tips here I'm able to advance through ages around the same time as moderate/hard AI (DE) and have some basic understanding of strategy and build orders.

I'm playing vs 2 moderate/hard AI. This typically occurs in early castle age, once I've set up 3 towns and am focussing on forward military production against one of the AI. Everything goes smoothly, except sometimes the other AI finds a gap and enters my first town with waves of knights (probably 10-12 at a time). My pikes and palisades are not much of a resistance, and by time I produce and bring 2-3 monks to the site, they've done enough damage to unnerve me (and force a resignation).

Looking at the stats post-match, I've got more vills and a bigger army at this point, so objectively, there is a reasonable chance of bouncing back if I somehow stick through the attack. During the match, however, it seems hopeless. I would like to know how you deal with this situation, particularly because I eventually want to play multiplayer team games, and then resigning like this wouldn't be cool.

Thanks a lot!