My husband invited his son from other woman to attend yesha's 1st birthday . How can I break the ice ?

For me, there's nothing wrong with inviting the child. As a father myself, the feeling of seeing my children get along with each other touches my heart all the time. How old is your husband's son? Does he already know the fact that he is his dad's son from another woman? Whether the answer is yes or no, it is a must thing not to make him feel discriminated. Let the kid enjoy the company of his dad. Also, send my appreciation to your husband. Not turning away from his responsibility is a brave thing to do and you should support him in his decision. Always remember, the child is always innocent. Don't make him feel out of place and neglected. Introduce yourself as his second mom and show him your acceptance, it can definitely be an ice breaker.