I’m pregnant but my husband has cancer

I just found out I’m 5 weeks pregnant with my second last week. I’m definitely excited but scared at the same time. My husband was diagnosed with stage 3 rectal cancer and we thought it wouldn’t be possible after the doctor told us his year long treatment course of chemo, radiation and surgery. The baby was conceived before his treatment so there shouldn’t be any side effects from chemo/radiation affecting his sperm quality. I just can’t shake the feeling something bad is going to happen.