Need advice 🫶🏽

So I just turned 18 in February and I’m currently 22 weeks and 6 days and I want to tell my grandma but I don’t know how to my mom and my grandparents don’t have the best relationship and it’s the same for me but my grandmas health is declining fast and I want her to know if she for some reason she leaves soon and I don’t know what to do especially because my grandma is toxic and won’t let me or my mom see her and I don’t him finding out because he is super  religious and will try and put me down …