Diet Blueberry Bread Pudding

• 1/2 lemon
• 500 gr blueberries
• 120 ml evaporated skim milk
• 26 gr sugar
• 14 gr diet margarine
• 8 gr cornstarch
• 1 gr orange peel (grated)
• 10 packages diet sweetener
• 4 slices stale diet bread