Dissolve gelatin in lemon juice. Let stand for 5 minutes. Beat egg yolks until thick and lemon colored. Combine egg yolks, half of the sugar and gelatin mixture in a saucepan. Cook over low heat and stir to thicken. Set aside to cool. Beat egg whites to form soft peaks. Add remaining sugar and continue to beat until peaks are stiff and glossy. Fold lemon mixture into egg whites. Whip the cream until medium stiff. Fold gently into lemon mixture. Cut angel food cake into 1" pieces and fold into lemon dessert. Spoon into serving dish and chill to set.