Just found out that I'm 3.5 months pregnant and my husband is sterile.

I'm 33 years old and I just found out that I'm 15 weeks pregnant. Just got back from my doctor and I have my first OB appointment in two weeks. My husband was diagnosed as sterile when he turned 22 years old. He has had trouble with his testicles his entire life, one of them never dropped. He had several surgeries and none of them worked. We've been together for three years and married for one. I just can't see myself raising a child with a stranger's sperm. I'm just really worried about how he's going to react.