Damn, I'd try never to let such a small force be caught so badly like that! I would mix my infantry with my archers, both loosely, and march towards the first 1000 enemies, with the cavalry escorting. Then, not considering some damage I would take, I'd have my archers firing, my infantrymen in front of them, and my cavalry charging the most vulnerable spot. If their reinforcements would come from behind, I'd have my archers joining my cavalry on melee, and my infantry attacking the enemy reinforcers. I'd try to die with honor and taking most of the enemy I could with me, to Heaven or hell.