Work can wait

Your work can wait. Don‘t let other people tell you otherwise. Also, don’t become emotional about it and rash your anger out to the next person who asks you to do something when you are at your limits.

Don‘t respond right away.
Take a deep breath.
Smile if you can. No matter if the person can see you or not.
Explain that this cannot be done right away.
Give them another slot.

If they insist and you think what they want indeed is important, ask them to do it after work hours. See if they are willing to do it at the cost of their over time as well.
If not gently push back and schedule it to next day or week. If this cannot be done, something is deeply wrong with your work environment.

The mindset behind pushing yourself beyond your own limits to please others on not time sensitive matters is usually based on either people pleasing nature of yourself or insecurity of your self in that ‘oh, what if I lose this job.

Don't underestimate yourself. You very likely can get another job. Might as well be something that pays you even better and treats you better. Renew your linked in profile and CV on a regular basis. Be ready to make the move if push actually comes to shove.

However, you cannot expect other people to treat you the way you want if you keep letting them force what they want without any resistance. Everyone has their own agenda and priorities. Unfortuantely many people will happily rid you of your free time to get a fast win.