Cry as much as you need to, you have to let it out. I can remember all too well waking up with tears in my eyes before I had even opened them in the first week or two, and bursting into tears at random times of the day. My OH was very supportive and this helps a lot, I hope yours is too, sounds like they are and them talking about the good times is good, especially when all you can focus on is the sadness, it gives some balance. Try not to expect too much of yourself, I imagined everyone else would be thinking I'd be over it in a day or two, and I put pressure on myself to put on a brave face and get over it, but I didn't need to really, your real friends will understand, and we here on RU will understand too. Talk to us whenever you need to xxx
Just wanted to add, those mixed feelings of guilt, questions, what if's, they are all normal, and I think part of the grief/healing process. Just let them come and go as they will.