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we call this "paradoxical praise"-- "Hank [the alcoholic] was well known in social establishments all over the metropolitan area," "Irma [the child beater] had a huge impact on the lives of her children," etc. The ancient rhetoricians taught this without embarrassment. It allows you to address both the naive and knowing listener all at once.
I recommend paradoxical praise, but something more. You should not allow the funeral situation to strip you of one bit of your full humanity. People there are not fine social crystal prone to crack upon cultural violation, but rich layers of knowing, feeling, valuing, and doing who are waiting for you to attempt to make some sense of our mortality. Try to do that.