Nicola Sturgeon maintained she has "done nothing wrong" as she appeared at the Scottish Parliament for the first time since being arrested.
Speaking about the "difficult situation", the former first minister said: "The thing that sustains me right now is the certainty that I have done nothing wrong."
Her comments came after she became the third high-profile SNP member to be arrested by Police Scotland as part of its investigation into what happened to about £600,000 raised by the party for independence campaigning.
Ms Sturgeon returned to Holyrood on Tuesday, nine days after being questioned by police and later released without charge.
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Speaking to journalists, she insisted: "I believe to my very, very core that I have done nothing wrong."
Her husband, former SNP chief executive Peter Murrell, has also been arrested as part of the Operation Branchform, as well as the then SNP treasurer Colin Beattie.
Both men were also released without charge pending further investigation after questioning.
With calls having been made for Ms Sturgeon to be suspended from the party while the police probe continues, the former first minister said she had considered "what is in the best interests of the SNP".
She told how the party had been "her life", describing members as her "extended family".
She added: "But I am also an individual that is entitled to assert what I believe to my very, very core, that I have done nothing wrong.
"I respect the process that is under way but I will continue to maintain that very clear position."
Ms Sturgeon added that if she stood aside from the party, that could "compromise my ability and my right to assert the position I hold absolutely - which is that I have done nothing wrong".
However she refused to speak about her husband's position - although she insisted people should not "read anything into" that "one way or the other".
The Glasgow Southside MSP said: "In a situation like this I can only speak for myself, and I am only speaking for myself.
"There is also a difference between me and my husband, I am an elected politician and a public servant, and there is an expectation, I think a legitimate expectation, that I make a statement and to the best of my ability answer questions. Obviously Peter is not in that position."
While calls have been made from both the SNP's opponents and some within the party for Ms Sturgeon to be suspended, her successor First Minister Humza Yousaf has refused to do so, saying he believes in "natural justice".
Ms Sturgeon praised her successor, saying: "Humza is doing a fantastic job as First Minister.
"When he was elected as First Minister I expected him to do a good job, I wish he hadn't faced some of the circumstances he has.
"But I am incredibly proud of the job he is doing, I think he is getting on with that on behalf of the people of Scotland."
Asked about her position within the party, she said: "It won't surprise anybody to hear that I search my soul on these questions on an ongoing basis.
"I have dedicated most of my life to the SNP. I don't say that to make it sound like a sacrifice, it has not been a sacrifice, the opportunities and experiences I have had in return have been immense.
"But the interests of the SNP are as close to my heart as is possible for anything to be."
She said she would "consider on an ongoing basis at all times what is in the best interests of the SNP".
