I am not sure where to place my feelings.

Where do I begin? To contextualize this ... I need to start from the beginning. I will try to keep it short.

My sister and husband got into a disagreement on a trip we (my mother, sister, her family, and our family friends with their kids) took together last summer. It was a stressful trip. Every. Single. Day. The result led to a rift in the entire family. To this day, my sister and husband haven't spoken and they (my sister and BIL) have since cut off all contact from him.

On the last weekend of the trip, my sister disrespected my husband in public by shouting and demanding that he wouldn't be able to find his way back if he took a certain route, and that he should just stay with the group. Our family friend had an overactive bladder and needed to use the restroom often, so my husband offered to take him. We were in a country whose primary language was not English (my family's heritage). My husband does not speak the language, but knows enough and is smart enough to navigate when given the chance.

My husband felt enraged and pleaded with me to say something to my sister. My fearful avoidant attachment style kicked in. I felt paralyzed. That night we didn't sleep. We fought the entire night and he threatened to head back home without me. Eventually, that would have led to our divorce. So, instead of him leaving alone, we left together, albeit abruptly. I felt so conflicted. I felt ashamed and immature. Yet, I couldn't voice my feelings to him.

Eventually, my husband and sister (10 years my senior) spoke on the phone. He explained to her what happened, how he felt. She defended herself and denied any responsibility.

Now fast forward, my mother at first stood by me, but now she is on my sister's side. She doesn't call me anymore and didn't visit for the holidays because she felt like she lost her daughters. My husband and I have fought to the point where we almost divorced.

Now I am conflicted because I want to repair the relationship with everyone, but it's been over 7 months. In a couple of weeks, my niece is graduating from high school. My husband doesn't want to be there, but I can't miss it (a three hour drive). Everything has changed within the family dynamic and the worst part is I have no one to run to... currently looking for a therapist, so I can take the steps to heal. My sister and I have communicated only through text about different things (relating to picking up my nieces to hang out, uncoupling some financial things). Other than that, nothing.

Sorry for this rant. I am not making any sense.
Is it wrong for me to see both perspectives in this feud? Did I bring shame to my family?

It's gotten to the point where some weeks, I'm having panic attacks at my job. Can't sleep certain nights. I have nightmares. I don't want to disappoint my family. I don't want to hurt my mom. I've hit rock bottom a few times. Turning to drinking excessively, afraid to bring it up to my husband how I'm feeling. Crying to myself all the time. Keeping my feelings hidden so my colleagues won't see.

My husband needs me to prioritize our marriage, but I also can't let go of my family. Am I just a major disappointment?