Well, considering that Jesus went to Peter's house and healed his mother-in-law from a fever she had, one could conclude, yes.
I heard an interesting point on Catholic Answers Radio about a month ago on this issue.
Apparently, Scripture records St. Peter had a mother-in-law yes, but no where does it record his wife was still alive, either when he met Jesus or anytime after that.
So it’s entirely possible he was a widower when he met Jesus.
Also, and this is what I found particularly interesting I don’t know why I didn’t think of it, he was at his mother-in-law’s house and she was the one waiting on them. I do believe if his wife was alive at the time, she would have been the one waiting on them at his (their) house.
Keep the faith; cousin!