Fetal Heart Defects

Currently 29 weeks. Around 22 weeks we FINALLY got into radiology for the anatomy scan of Marshmallow. We found out that we're having another boy! But we also got news that he has some rather severe heart defects and referred us to a better hospital for tests. We found out that baby for certain has an AV Canal Defect and that his heart is centered rather than on the left. They told us that there is a concern that baby may also have Transposition of the Greater Vessels but they won't know for certain until baby is born and they can do an echo on him. The way I understand it all, is that while the AV defect is serious, the Transposition poses the biggest risk and danger, and if he does have it he will require IMMEDIATE heart surgery. Is there anyone out there who has gone through this or something similar that could tell their story or direct us to some support resources? The doctors did inform us that the AV Canal defect typically occurs in conjunction with Down's Syndrome, so while its the least of our worries, my heart stl hurts for this baby boy who has so much to face already. I refuse the chromosomal test (I don't know how to spell it) because of the risk and strong probability of inaccuracies, and even if it came back as an accurate positive..it wouldn't change anything. If it tested for something that was treatable I'd consider it, but otherwise it just seems like an unnecessary risk. I'm so scared that I am not going to be the Mommy this little one deserves...I'm just so scared and heartbroken for my baby, and the uncertainty of it all makes it so much more difficult. I broke down yesterday while purchasing a few premie onsies because I don't know if I'm picking out a going home outfit or a funeral outfit. Any support, thoughts, prayers, or advice is welome.