Maureen Cassidy has resigned her position as deputy mayor for London, stating her relationship with Mayor Matt Brown "crossed a professional boundary." The mayor is taking a leave.

The announcement rocked council Tuesday evening, with some members becoming emotional.

The mayor was not at council but issueed a statement confirming an "inappropriate personal relationship" with Cassidy for a "brief period of time."

"This was a grave error in judgement on my part," he wrote. "The relationship ended some time ago."

Brown indicated he will take some time away from his office and will return when he and his family are ready.

I love my family and I love my work as mayor of London. I look forward to continuing that work over the next number of years, even as I find a better balance between the demands of my job, and the needs of my wife and family."

Brown noted he will meet with the new integrity commissioner on Thursday.

"While I do not believe my relationship with the Deputy Mayor resulted in any breach of my professional responsibilities as Mayor, I nonetheless want to obtain his opinion to ensure that there are no issues. I will abide by any decisions or recommendations of the Commissioner," he wrote.

In her statement, Cassidy said she caused pain to both her family and the Brown family.

"This is something which I regret immensely. I have caused my family horrible pain and embarrassment and for this I could never apologize enough. I know this has also hurt the Brown family deeply and for this I am very sorry."

She apologized to her council colleagues for the disruption and distraction it has caused.

Cassidy said her family is now working to try to build trust again.

Deputy Mayor Paul Hubert will become acting mayor on Wednesday.

Here is the full statement sent out by the mayor on Tuesday:

Statement from Mayor Matt Brown:

In recent days there have been rumours circulating about my private life. Out of fairness for my colleagues and my family, I believe the best course of action is to address them directly.

I can confirm what some have speculated. Over the past many months, during a period of intense workload, I developed a close working relationship and ultimately an inappropriate personal relationship with Deputy Mayor Maureen Cassidy, for a brief period of time. This was a grave error in judgement on my part. The relationship ended sometime ago.

I am deeply sorry for the pain that this has caused – for my wife, my family and everyone involved. I make no excuses for my behavior and my poor judgement in my personal life.

Justifiably, my wife Andrea was extremely angry with me when I told her of the affair. My actions have put a tremendous strain on our relationship. Despite this, she has committed to working through this together and doing what we need to repair the damage I have caused to our marriage.

I love my wife, and we are working through our private issues together, with the help of marriage counselling and the minister of our Church, who has been a true friend to us.

I realize there will be many questions related to my personal and my professional life. In light of that, I will sit down with the integrity commissioner on Thursday. While I do not believe my relationship with the Deputy Mayor resulted in any breach of my professional responsibilities as Mayor, I nonetheless want to obtain his opinion to ensure that there are no issues. I will abide by any decisions or recommendations of the Commissioner.

I want to be as open and transparent as possible. I have made a grave error and I need to own that.

But, I also ask that members of the media and our London community respect the need of my wife and children for some privacy as we work through this difficult time.

I love my family and I love my work as mayor of London. I look forward to continuing that work over the next number of years, even as I find a better balance between the demands of my job, and the needs of my wife and family.

My primary focus must always be to earn the love and respect of Andrea and my family.

I intend to spend more time with my children and my wife in the coming weeks. I’m taking some time away over the next little while and I will return to my other duties when we’re ready.