In an interview in the November issue of British Marie Claire magazine, the 35 year-old said: 'I was hard on myself when I got divorced. Until I got remarried, I don't think I realised how stressed I'd been.'
After getting married again to Jim Toth in March, the Water for Elephants star said she could finally breathe a sigh of relief.
Witherspoon added: 'I don't think I recognised how anxious I was about being a single parent. It was really, really stressful. It's not easy on anybody - it's really traumatic.'
The Oscar-winning actress also said that Toth gets on well with her children - Ava, 12, and Deacon, seven.