I have ms and I was wondering if ms is untreated and I get brain lesions can brain lesions cause death if so?

No, MS lesions do not bleed, an MS lesion is not like an aneurysm. It might help if you think of it as the myelin sheath being eaten away by the attacking immune system.

You cannot treat the lesions (although hopefully one day that will be possible), only wait for them to heal up on their own. With relapsing-remitting MS, sometimes an intensive steroid treatment at the onset of an attack will help speed up the healing process.

The current MS treatment is symptom treatment and disease modifying drugs (for relapsing-remitting MS). The disease modifying drugs do not heal existing lesions, but they help prevent new lesions.

Your brain lesions will not cause death, but they can cause a number of other issues, all depending on where they're localised. MS is not considered a fatal disease and people with MS have near normal lifespans. What you can die from are secondary issues. E.g. if the MS at one point have you bedridden, then your risk of pneumonia etc. will be higher.