to be honest

https://www.collinsdictionary.com/dictionary/english/to-be-honest 

Typically used before you give your views on a subject, especially if what you are going to say might disappoint/upset the person you are talking to, or run counter to their expectations. 

Brothers Gary and Martin Kemp were founding members of the 1980s legendary band Spandau Ballet. In this mockumentary (a parody of a documentary), they pretend not to get on well, and to be jealous of each other. 

Desert Island Discs- interview with George Michael- watch on Vimeo

(click on "CC" to turn on the subtitles)

The late singer George Michael explains how one of his best albums, Older, deals with the pain of his first partner's death. 

Derry Girls s2 ep02- The girls have been caught red-handed breaking a religious statue at school as revenge against the school for allegedly firing their favourite teacher. 

W1A- s1 ep 02

It's a Sin- To be honest, 

Hugh Laurie  (Desert Island Discs, BBC Radio 4, 1996)- answering a question about the sudden disappearance of his friend Stephen Fry some months before due to stage fright. 

HL: To be honest with you, …It's difficult to answer for him. 

Host: No, quite

Zoey's Extraordinary Playlist s1 ep 02

Hugh Grant, Desert Island Discs (BBC Radio 4, 1995)- explaining how, after starring in the hit romantic comedy Four Weddings and a Funeral, Hollywood studios allowed him some power to decide over his following projects. 

…but it's much harder than I thought, to be absolutely honest with you, …

I don't know about you, but I've found this week a bit of a struggle, to be totally honest. 

The Durrells s01 ep 03