The Munstermen went down 33-10 to Saracens at Allianz Park to crash out of Europe but still face a final pool game with Sale Sharks this weekend.
Munster's European struggles are in stark contrast to their GUINNESS PRO12 form, where they sit third in the table just two points behind leaders Ospreys.
And while Foley admits that it has been an unpleasant week for his troops, he is adamant they are poised to bounce back in style against Sale.
"It's been a long few days. A very long few days. A very dark few days," Foley told the Irish Examiner. "We're all gutted, shattered, whatever word you want to use. We need to deal with that ourselves.
"It's hard - people will question you. People will ask why it is happening because they don't expect it.
"We let ourselves down - we don't need anybody telling us that. We're all clued in enough to understand that and where we are.
"It's not easy but it does motivate you to get to the better days. It drives you to make sure these days don't come back again. When we lift trophies, those will be the moments we know we have earned it.
"I also think the people that have supported us throughout our careers and have looked after us are the ones probably getting hurt.
"If anything it will drive us Sunday to get a smile on the faces of people that really care about us. That will be the real motivation."
Follow us on Facebook, join the conversation on Twitter, sign up to our YouTube channel for extensive match highlights and sign up for our newsletter for regular updates on the GUINNESS PRO12.
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland