I can't imagine that anyone would judge you harshly--you've been so kind to the kids. I don't think the fact that her ex MIL paid for the urn obligates you to be responsible for her remains. Seems to me you've got a couple of options. I don't think holding onto the ashes would be healthy for you, to be honest. I'd suggest one of the following: scatter them privately in a place that's meaningful for you. Give them to her kids, with the explanation that you feel they are the most rightful custodians, after giving it a lot of thought. OR pay for a memorial niche at your local cemetery and leave them there. Any one of those is respectful of her memory, without having the constant reminder in your home.