This is a tricky one to answer without knowing more about your specific situation. If I have misconstrued your question then please add more detail so others don't also get the same impression.
Are you a willing participant, or an unwilling one?
If you are unwilling, to what degree? Is it just a casual nuisance (someone comes home from training and wants to use you as a reluctant training partner), or this is a domestic abuse situation?.
If this is domestic abuse, get the authorities involved now - there is no such thing as "too soon".
If you are simply a reluctant participant in someone else's games, then learning to hit back is not necessarily the right answer either. There is no magic switch you can hit to just stop someone - not without a lot of practice and training. You "don't want to escalate", so this leaves one option - use your words. If you can't have a serious conversation with this person to stop this behaviour, then refer back to my previous answer - get outside help now.
But just to be really clear (in case I wasn't): we cannot and will not teach you or coach you out of a personal situation that involves violence. In situations like this you need to reach out and get assistance from those around you, including friends, family, law enforcement and social agencies.