Counter cavalry question

[Squiggles]

On a 2v2 I have run into a problem with a new strategy has been wrecking me and I need help.
The technique is one player has a balanced army and the other player has all cavalry a mix of Yari, light and katana cavalry they always go for the person they feel is more of a threat so that would be me. I usually do fine until I see that ten units of cavalry are behind me. I can’t use more spear units then my infantry is weakened and my monks will get mowed down by bow and matchlock units. If you any ideas let me know in the comments. Or am I just always going to get defeated?

Thanks for your time.