The `Fighter` singer - who filed for divorce from husband Jordan Bratman this week - wants to make the separation as easy as possible for two-year-old Max and has vowed to be with him as much as possible.
A source said: "She`s focusing on continuing to be a great mom. She`s spending as much time as she can with Max.
"Max is her number one concern. She`s making a huge effort to continue to be a good mom through this transition for him.
"It`s hard. You`ve got to handle it with dignity. I don`t think they`ve figured out everything yet. They have a child together, so they`re trying to do what`s best.
"Christina wants to be the first face Max sees in the morning, and wants to be the one to put him to bed at night."
On 14.10.10 the 29-year-old star took Max to Mr. Bones Pumpkin Patch in West Hollywood and onlookers insist she showed no sign of the strain of recent events.
One source told People.com: "Christina was in a cheerful mood and seemed to have a blast with her son Max. It was obvious that Christina was trying to have a fun outing and make things special for Max. Max looked very happy to be out with his mom.
"Christina looked anything but sad and it`s hard to believe that she is going through a difficult break-up. She seemed very strong and just focused on keeping things normal for her adorable son."
Christina and Jordan reportedly signed a prenuptial agreement prior to tying the knot, which will determine who gets what in the divorce settlement.
It is believed the couple are seeking joint physical and legal custody of Max.
However, the petition states the singer will block any attempt made by her husband to receive child support from her.
The singer released a statement on Tuesday (12.10.10) confirming the pair had broken up.
She said: "Although Jordan and I are separated, our commitment to our son Max remains as strong as ever."