I'm so very sorry for your loss, but definitely do not hold it in. That could build up stress within, causing increased blood pressure, etc. It's OK to cry and mourn. If you have someone close, get with them and ask them to either cry with you or just be a shoulder. Find memories of him that will make you laugh and concentrate on those. And know that he'll be watching over you and your babies always now. Talk to him every chance you feel the urge and he'll be there listening, though you maybe not get his response.
I know your pain. My mom died the day of my 9 week appointment. She was the only person I had told and we were both worried because I had a missed miscarriage a couple of months before. She never got to hear the heartbeat or find out that we're having a boy. It gets easier over time but take the time to mourn and depend on those around you who love you.