How to discuss fears with partner.

MandaAUS

I had my first child coming up 13 years ago. I was told when he was 6mths that conceiving another child would be a major challenge and possibly require IVF. After two relationship break downs I met my fiance'. At 35yrs I decided to give IVF a go so we started changing our life style to start IVF. I quit drinking, smoking and started eating healthier and we were starting to put away money to pay for the IVF. 4 weeks after starting our changes unexpectedly but certainly totally wanted we managed to fall pregnant naturally. So here are the steps that have lead us to being in a complicated situation where I feel I cannot get support from him.

With the complications with my ovaries and fallopian tubes my Dr was concerned right off the bat that it might be a tubal pregnancy. (1st scare) At 5w5d we had a scan to tell us it was not a tubal pregnancy. 

At about 8w we went into hospital because I was cramping way to much (2nd scare) Dr's thought it might be due to my appendix and after 5 hours being in hospital I opted to go home as I had had enough. Tests reveled that everything was ok. 

At 12w we had our NT scan (3rd scare) The results came back all clear on the US but the bloods showed a different story. Hormone levels are high. I now have been booked in for an amniocentesis. (4th scare) 

So far during the pregnancy I have been referring to everything in a medical / clinical way because I am scared about something being wrong. I haven't want to make plans or talk about the future yet as I'm scared that will be taken away from me. Yes friends and family know I'm pregnant but they also know at the moment there are high risks associated with the pregnancy a 1:128 chance of downs or something else. 

Now for the problem. Up until recently my partner has been less than vocal about the pregnancy which to be honest has helped. It as meant that its not been in my face and real. Until the other night where he (without consulting me) announced to one of his friends that he will be the god father. Making plans and such without thought of how I might feel about it. We argued and he kept saying that hes proud of the pregnancy and that he should be allowed to talk about it but I feel that he doesn't understand that after 12 years struggling to conceive this baby I'm scared something will do wrong so I am trying to distance myself until I have the results from the amnio back. 

How can I get him to understand that. Or am I being the one in the wrong here ?
Please help, I'm afraid my relationship might be in jeopardy because of the situation.