Interview HELP please?!

Kr
Hi, so I'm in a job I hate right now, I'm a teacher in NY and jobs are few and far between so I'm here and sucking it up daily. Well I interviewed for a job 2 weeks ago and I got it! Great right! But it was at a very similar school w more pay so I weighed the pros and cons and being 18 weeks prego I figured it wasn't the best idea to take a job teaching only to have to leave it in a few months. Not too mention I won't have FMLA at my new job. So I was happy w the decision, this other place was understanding and I don't have to move anything or stress over starting my job mid school year. Well I just got a call from a public city school I've been wanting to get into. Great insurance, amazing benefits, job security... Well I can't lose this I need this it's what I've wanted so what do I do? If I go for the interview do I tell them during the interview? Should I wait till I get it offered to me? Or ask them ahead of time. To be perfectly honest, the start of starting mid year moving my classroom, having new insurance and no FMLA this close to having the babies is stressing me out!! But this is such a huge huge opportunity if I let it go I could be black listed! I don't know what to do!!! Help! Anyone ever in a similar position?