Is it acceptable to wear my mom's wedding dress even if her marriage ended in a divorce?
Did that marriage result in you? Surely that makes it a success even if it didn't work out in the long term. If your mum's happy about you wearing it and you want to then you should do it. If it's acceptable to you then it's acceptable!
I think you can do what you want, but personally I'm a little supersticious so wouldn't as its supposed to pass on good luck from a happy couple to you, same with your something borrowed. You should also ask your mom if she'd mind. Would it upset her to see it again? I know my mom wouldnt even want to see hers again and shes divorced too.