riddle - Necessary to live, painful to bear

I burn without flame, though you may disagree,
I understand your pain, which stings worse than a bee.

I rupture easily, even though I can last forever,
I surcease uneasily, I will affect you whenever.

I trap people, who are tied to the past.

What am I?

Answer

A heart

I burn without flame, though you may disagree,

Heart burn

I understand your pain, which stings worse than a bee.

Human heart can feel many emotions, some of which are empathy and sympathy.

I rupture easily, even though I can last forever,

today an enlarged heart or a blocked heart are more common, but usually it will last throughout your entire lifetime without much problem.

I surcease uneasily, I will affect you whenever.

your heart can technically stop at any time, and affects you greatly.

I trap people, who are tied to the past.

people can be stuck in regret with a heavy heart. they are trapped in their memories and their feelings, all of which affect the heart's function- after all, people (and animals) can die of depression.

The acrostic:

burst (minus the "I" to find it.) Your heart can burst with joy, with regret, etc.