Is it considered forbidden for a married woman and mother to send her picture online to a foreign man?

Firstly: These conversations are forbidden if they lead to temptation and evil.

Secondly: You must repent to Allah and seek forgiveness for this forbidden act, regret it, and immediately stop conversing with non-mahram (definition) men, while increasing your supplications for Allah to conceal you, and occupying your time with what benefits you in your religious and worldly affairs, such as learning religious matters, taking care of your husband and children, and befriending righteous women.