Cystic Hygroma

I had my 12 week appointment yesterday and they found a cystic hygroma (fluid behind the neck) that’s around 7-8mm. I am now being referred to a specialist. From what I have read about 50% means it’s a chromosome issue or 50% is heart defects. Anyone been through this before? We are devastated of course and I’m trying so hard to be optimistic. I’m 37yrs old so I knew we may face something like this but we are crushed. This is my third pregnancy. I have a 3 yr old boy and I had a miscarriage back in Oct 2022.