The Heather Trott actress, who was evicted from Celebrity Big Brother on Friday, stated that she has "only very recently" moved on from the BBC soap.
Fergison's character Heather was killed by Ben Mitchell in March, after the 48-year-old's contract was terminated by producers.
She told the Daily Star: "I didn't allow myself to have a grieving process when I left EastEnders. When they killed me off it was like losing my family or losing my friends.
"Suddenly not being part of a secure institution was hard. Only very recently have I finally put my grieving process away. That is what I really needed."
Meanwhile, appearing to criticise the on-screen fallout from Heather's death, the star is quoted as claiming that bosses "could regret" writing her out.
"They could regret it. Although I think the storyline has gone on and on for too long," she added. "But I only expected to be there for three years at first, so every year was a bonus. You can never take anything for granted on EastEnders."
Speaking more positively, Fergison revealed that she is glad she will not be offered the chance to return to EastEnders, adding: "The temptation is always there for actors, especially if they tempt you with money and you haven't been working much. But I won't have that problem."