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Much of Hollywood was shocked when Jennifer Lopez and Marc Anthony abruptly announced the end of their seven-year marriage on Friday. But those closest to Lopez, 41, and Anthony, 42, tell Us Weekly that the couple had been struggling for years.

Singer-actress Lopez "tried everything she could to make it work," one source close to the star tells Us. "They went to marriage counseling. She was patient and loving and did everything he wanted her to.. She exhausted all the possibilities."

"They had a very up and down marriage," adds a second source of the couple, parents to 3-year-old twins Max and Emme. "They would get into heated, horrible fights. Then, they would also go through times where they were extremely loving and romantic...It was a roller coaster with them from the beginning."

According to several pals, Lopez will likely remain in Los Angeles with primary custody of her son and daughter.

As she rebuilds her life as a newly-single mom, "She is devastated," the first source admits. "Absolutely beside herself. This is someone she dedicated a long time to, and that she truly loved. "

One thing to keep her busy? A slew of projects in the pipeline, including a new Kohl's clothing line, a new romantic comedy What To Expect When You're Expecting (shooting starts next month) and, likely, a return engagement to American Idol.

Despite her broken heart, "She is looking forward to the future," a third insider says. "She is jumping back into work and being a mom with all her energy and she is really excited. She feels like she has grown leaps and bounds and is a new person now, better than ever!"