The 27-year-old finished sixth in the final and was disappointed not to be able to win a medal for his “role model”.
"My mum’s been putting in such a shift for me over the last 27 years and that's probably the main disappointment,” an emotional Wilby said afterwards.
"I know I've made her proud, but I haven't quite won the medal I would like to have won for her.
"She's been working as a nurse giving out vaccines recently which makes me so proud of her, and for what's she done for me and my brother over the last few years.
"She's the role model in all this; I hope she enjoyed watching that."
The race, which was won by Australia’s Zac Stubblety-Cook, could be Wilby’s final participation in the Tokyo 2020 Olympics. He is part of the men’s 4x100m medley relay group but the breaststroke leg is likely to be taken by Adam Peaty.
Wilby finished fifth behind his GB colleague in Monday’s 100m breaststroke final and will be 30 by the time of the next Games at Paris in 2024, but remains adamant that he has a crucial supporting role to play in the remaining swim events in Tokyo.
"There are some people who I train with and am very close with. I want to be there to help wherever I can.
"If I get a chance to swim again, I'll be ready to put this behind me and put in a good effort for the team."