A former member of the Islamic State in Iraq and Syria (ISIS) has given CBS News a detailed look at what life is like under the terror group's reign. The man, whose voice is altered and whose face we cannot show, recently left ISIS and is trying to get home. He was interviewed by CBS News correspondent Clarissa Ward.

Abu Ibrahim is one of thousands of westerners who have traveled to Syria to fight jihad.

"A lot of people when they come, they have a lot of enthusiasm about what they've seen online or what they've seen on YouTube," Ibrahim told me. "They see it as something a lot grander than what the reality is. It's not all military parades or it's not all victories."

CBS News' Clarissa Ward interviews ex-ISIS member Abu Ibrahim CBS News

A convert to Islam, Ibrahim wanted the chance to live under strict Islamic Sharia law so he joined the most extreme group there - ISIS. During his six months with the militants he saw crucifixions. In December, he witnessed the stoning to death of a couple convicted of adultery.

"It was done publicly," said Ibrahim. "There were many hundreds of people there who observed. While seeing someone die is not something anyone would probably want to see, having the actual Sharia established is what many Muslims look forward to."

Ibrahim told me the methods don't strike him as medieval: "It's harsh, it's real but it's the Sharia," he said.

He described the role of the Hisbah - the religious police - in the Islamic State. He says their role is to enforce Islamic code.

"Their presence which may deter any thieves or any bad behavior but also look out for things like music isn't being played or women are covered up appropriately or that men are growing their beards," he said.

Life for western jihadists under ISIS' rule is almost completely subsidized. Ibrahim told us they provide housing, food and an allowance.

"Initially it was approximately $50 a month," Ibrahim said. "During winter it went up to $100 so people could purchase warm clothing or items for the house. They provided heaters for each house and for married couples they provide housing for them - furniture, the essentials."

But there is one condition: once you join ISIS, it is virtually impossible to leave.

"The restrictions on leaving made it feel a bit like a prison in that respect that you couldn't leave the state," Ibrahim told me. "Myself if I was caught I would probably be imprisoned and questioned."

Ibrahim says ISIS is paranoid about spying and is worried about infiltration. Those found guilty of spying are executed.

Despite the risk, Abu Ibrahim began to look for a way out. He was increasingly disillusioned by the executions of western aid workers and journalists.

"Some of the policies such as the beheadings of non-combatants, therefore innocent, some of those things I didn't agree with," Ibrahim said.

He missed his family and felt bored - jihad wasn't what he thought it would be.

"My main reason for leaving was that I felt that I wasn't doing what I had initially come for and that's to help in a humanitarian sense the people of Syria," he told me. "It had become something else. So, therefore, no longer justified me being away from my family."

He described morale within the ranks as "pretty strong," but mentioned there are some who are growing disillusioned.

"There's a lot of enthusiasm but there's also some people who are not so enthusiastic, who are even scared," Ibrahim said. "Obviously with the coalition, things have become much more difficult."

Ibrahim told me his departure from ISIS isn't something he thinks he'll miss.

"I'll miss the friends I made and the brotherhood, but ISIS itself - no."