I need advice

My boyfriend and I recently Discovered at the doctors that he has zero sperm count due to him having cancer years ago. thankfully he banked his sperm before treatment so we have to do IUI . . this has been really tough for me I feel like I have no one to talk to considering my mom passed away a few years ago . I just feel so alone about this whole thing . His mom has no idea we were trying to have a baby or what the situation is right now so I was thinking about telling her but I don’t know how to say it . I know she won’t be mad considering she has 3 grandchildren but I’m just scared . any thoughts Or opinions? Thank you