How do you know it's time to end a relationship?

Hi I want to know if I should leave my husband . We have been with each other for almost 29 years and been married for almost 17 years. He as 3 children from 3 different women. And I have his last 2 children and only girl. He was married to the first girl he was with and divorced after 4 years. Recently she has been on social media posting to his sisters and mother and calling them her mother and sister in laws . Not ex in law’s. I told my husband to get on there and tell her she needs to rephrase it and have it say ex in laws. But he refuses to do it saying he doesn’t want his son who is almost 40 to get upset with him. But this isn’t the only thing his mother and siblings do the same and I feel very disrespected … there is just so much that his family and his exes have done in the past and he has never stood up for me and he makes me fell like I am being petty about it all. When I am not I feel I am the one who had stood by him and never given up and am still here and I deserve to be respected.