Pop star Jessica Simpson insists she knew it was time to leave ex-husband Nick Lachey when she went on a charity mission to Africa on their anniversary and he opted to stay home. The singer went to Africa last year (05) on behalf of Operation Smile which helps children with facial deformities. She explains, "I went there on our three-year wedding anniversary. He stayed home. On that day, everything became so clear. "I was in hospitals with all these sick kids, and I was looking at the beauty of this whole different world. I just knew I needed to find something more in my life - on my own. "I prayed, then looked up at the sky, and I'd never seen this before - it was a double rainbow. It was the most gorgeous thing ever. "From that moment on, I've listened to Judy Garland's SOMEWHERE OVER THE RAINBOW every single day." Soon after Simpson returned home, she told Lachey she wanted a divorce. She adds, "At some point we realised that everything is not what we expected it to be, as hurtful as that may be."