4 1/2 pints
Combine 1 cup black raspberry juice, red raspberries and strawberries in medium-size kettle. Soften unflavored gelatin in remaining ½ cup raspberry juice. Bring fruit mixture to a boil. Whisk in xylitol and Gentle Sweet. Add softened gelatin and strawberry jell-o. Whisk until well combined. Bring to a boil. Ladle into jars, add lids and rings. Cool. 4-5 pints jam.
This method is what I use when I store the jam in the fridge. If you want to store it in your pantry you will need to hot water bath it. Place it in a canner with 1 inch of water over the top of the jars. Boil for 10 minutes with a gentle boil. Remove jars and allow them to cool.