Short answer
Private marital matters should generally be protected, while serious problems may appropriately be shared with a trusted mediator or professional.
Islamic Guidance
What Islam teaches
Islam values privacy and prohibits harmful gossip. Seeking help to resolve serious marital problems is different from publicly exposing a spouse's private matters.
Practical Guidance
What you can consider
Choose a small number of trustworthy people if outside help is necessary. Avoid forwarding private messages, photographs or accusations to others.
Sources
Qur'an 49:12; Qur'an 4:35.