Not so happy birthday

It's my 25th birthday today. It's also the day after I found out I'm having a chemical pregnancy or an early pregnancy.

My fiance already had plans to work on our house today and his family is coming over to help him. I can't be around people right now, without feeling like I'm going to burst into tears, so I'm going on a small day trip by myself.

He wants to stay home and work on the house (we're building it ourselves) instead of missing a day of work to come with me. I feel guilty being upset because he's quite actually building our house, but I'm frustrated that after everything he won't spend the day with me.

Am I wrong? I feel horrible for being upset with him over this.