The `Two and a Half Men` star - who has 13-month-old twin sons Max and Bob with wife Brooke Mueller - has reportedly been leaving the Californian rehabilitation clinic where he is receiving treatment for alcoholism to meet with Angelina Tracy.
A neighbour of Angelina - who also works as an escort who charges $3,000-an-hour - claims to have seen Charlie entering her apartment several times, with the actor donning a fake moustache as a disguise.
Speaking of an afternoon meeting last Wednesday (07.04.10), the neighbour told In Touch Weekly magazine: "He ran down to his car. It seemed like he wanted to leave as quickly as possible."
On another recent trip, Angelina was seen running down her stairs and getting into the actor-s chauffer-driven car.
The source added: "Charlie had a bouquet of flowers waiting for her, and her face lit up when he handed them to her. You could see them kissing on the lips. He gave her other gifts too - maybe clothes or lingerie."
Despite his alleged infidelity, the 44-year-old star is said to have promised Brooke - who is also undergoing treatment for addiction problems with alcohol and crack cocaine - he is on the road to recovery.
A source said: "He is seeing Brooke and the kids a lot and is good about continuing treatment. He has been sweet to Brooke, and promises her that he-s changed."