J.M.
Your feelings sound perfectly normal for what you have been through. You loved Nick and wanted a life with him and you were robed of that. His death was tragic, but he died knowing you loved him. Nick had something very wrong with his health and would have died from a stroke very soon, even if you had not made love. He died being close to his wife, rather then at work or driving alone. I think if he had a choice he would have chosen to die the way he did. You have nothing to feel guilty about. You were a good wife.
And now you have gone on with your life, that is the best thing you could do. You have a new family and I am sure they love and need you. It is ok to let yourself be happy
and enjoy your family.
Please take good care of your self
J.