How do you ever become happy again after losing a loved one?

Sorry for your losses. I don't think anyone actually could "get over it", their deaths will forever stay in your mind, in the back or in the front when you see a picture of them. Remember the happy, fun times you have had with them. The sadness will leave and you will once again have a smile on your face. If it's either someone making you laugh or remembering a cherished memory of them. Cheer up! They would want you to be happy and know they are in a better place.