I'm so very sorry for your terribly sad loss. What a tragic situation. My heart goes out to you and your family.
It's totally understandable how you are now feeling, and I'm a quite suprised that a doctor would tie your tubes during such an emotional time. I do hope you have some good support around you to help you through this, and listen to how you are feeling.
I'm afraid I can't offer you any advice about your situation in regards getting pg again. I assume IVF would be able to assist you as a medical procedure is used to retrieve your eggs and your fallopian tubes would not be needed. That said, IVF is costly and fairly invasive. I guess you would need to weigh up all the pros and cons of reversal of your original procedure against IVF. I don't know what other options could be out there....hopefully some else will post that understands better. I too suggest you visit the IVF board. I will go find a link for you and post it next...
good luck to you
you and your little angel Marcus are in my thoughts