The Labour councillor is stepping down from Sandwell Council after 21 years to spend more time with her family in Cornwall.
Originally elected for the Conservatives Councillor Costigan was deputy leader when she defected to Labour in 2010 blaming then Education Secretary Michael Gove who announced the Government would rebuild several local schools before changing his mind the next day.
Councillor Costigan believes what she will miss most from local politics is having a cup of tea with her constituents.
She said: "I retire from public office next May, it’s been a privilege to represent Wednesbury North for 21 years.
"I’ve tried my very best and helped so many, did good deeds getting the job done, and helping people financially, passports signed driving licences plus regular visits to the elderly simply having a cuppa with them.
"I’ve loved every single minute of it, and made so many life long friends."
Councillor Costigan's stretch in office coincided with a tumultuous time in Sandwell politics with bitter divisions within Labour which led to several suspensions and dismissals from the party. The former Wood Green High School pupil admitted she will not miss the rough and tumble of local politics.
She said: "At times it’s been tough to deal with when I’ve seen and been part of things I disagree with, but in my heart it had to be done, I like fairness and as I’m a bit of a softie and have been taken advantage of.
"But I wish everyone well what ever path they choose, I’ve moved to Brewood pending retirement to be close to my family and spend more time with my wonderful husband.
"Wednesbury will always be close to my heart as when I lost my mum and dad 2018 and 2019 and that made me realise just what’s important and you know when the times right, and this time is right for me.
"I will always pop back and still help a community group called Let’s Dance Again who do so much for Wednesbury and surrounding areas, they are honest and wonderful people who just want to help the elderly."
She added: "I’m still available until May to help anything people need. Love you all no matter how you feel."
Constituents and friends posted messages of thanks and support on social media after Councillor Costigan revealed she was stepping down.
Sarah Curran said: "Good luck in your retirement , many thanks for all your hard work. Put your feet up & enjoy your quality time with your beautiful family."
Heather Jones added: "Thank you for your service Elaine Costigan you have done wonderful things for a lot of people of Wednesbury and them who truly know you, know you did everything to the best of your ability as you always do."