my husband got another woman pregnant… now what?

So, here’s the situation: my husband (42 M) got his 24-year-old girlfriend pregnant, and now I have to figure out how to tell our kids that they’re going to have a half-sibling. I've been sick with cancer for 8 years, and I’m not going to lie, I’ve changed a lot physically and emotionally. I get why it happened, though it doesn’t make it any easier. I’ve known for a while things weren’t perfect between us, but I never expected this. My husband isn’t leaving me for her, but he asked me to help break the news to the kids, and I honestly have no clue where to even begin. How do you even start a conversation like this? Anyone been through something similar? Any advice would really help me right now. #marriage #infidelity #familydrama