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Hey!

I'm sorry to hear that you are going through this.

If your mom or family asks you again to take sides, I would respectfully tell them that you do not feel comfortable doing this. You can say something along the lines of, "I understand that this is a really stressful time for you, but I do not feel comfortable taking sides in this matter." If you don't want them talking about it around you you can also ask them not to by saying, "Please do not continue to talk to me about the issues with my sister." It's not fair to you that she is talking badly about your sibling and putting you in such a tough place.

I understand not wanting to turn on your sister without hearing her side, so I'm sorry that you can't get in touch with her. If your older sister truly did these things though it sounds like it would be a good idea to take a step back. If you feel comfortable you can ask her why she did it if you ever are able to get in contact with her again, but if you aren't able to get in contact with her you don't have to guess reasons why either. But if she is truly talking about you and distorting your stories it may be a good idea to evaluate how you want the relationship to proceed when you do get in contact with her again. Do you feel comfortable sharing your secrets with her anymore, for example?

You don't have to make any decisions on what to do or say without putting thought into it first to see where you stand. You don't even have to take sides if you don't want to.