Stressing like crazy!

I don't know if I'm just seriously hormonal but I'm so stressed about work and feel like I'm being pushed out since I announced my pregnancy!

I only announced it yesterday and my boss has already emailed today requesting passwords for log ins to take over some of my work load since I'm "leaving". She's also talking about hiring someone to take over my position already, when I feel the normal practice would be to hire a temp to take over temporarily.

My partner is a resident pending his citizenship application but my visa agent was shockingly slack and I'm still waiting on my residency so I'm already stressing about the lack of income support I will receive whilst on maternity. My company have no HR and my manager is clueless as to whether I will be provided any maternity pay. I'm not big headed but I'm the longest standing employee by years, work the hardest & have the most experience in this area of work. I'm so worried things will change for me after I have the babies (I say babies because I'm having twins!)

Any advise would be so appretiated, I'm going out of my mind xxx