Pregnant and shocked help!

So I’m freaking out because I just found out I’m pregnant again after being diagnosed with pcos and told my chances were very slim, I have another son whose 16 months and I just feel so guilty and sad and confused, scared like I feel so bad for him? I don’t feel the excitement I felt with him and I can’t stop crying. I’m just venting because I literally don’t know what else to do, my fiancé is being so supportive and nice and not freaking out at all. When I heard I had pcos I was upset but I wasn’t ready to have another baby so I didn’t 100% care but I went to urgent care thinking I had the flu and bam, is this normal? What do I do and how can I cope with this? I just feel so lost and so scared for people to know. I don’t even know what to say I’m just shocked.