Should i leave for the better or stay and fight?

Husband and i were previously seperated a yr ago. Within that yr he got my second cousin pregnant. They currently have a 3 month old. Now i know it isnt the babies fault. So i try and be the better bigger person. Through out the yr of the seperation i hit a hard depression when i found out the news. I tried committing suicide. I was hurtimg so much. Him and i have 3 baby boys together. So i came back home when he asked me too and im trying to do thing's right. But she wont allow him to see the baby if im around. Idk how thats gunna work out. She says im a hsrm to her son and she wont allow it. That means as long as im with my husband he cant see his kid with her. I dont want to feel like a burden. What im getting at is ..shpuld i stay and fight some more or should i just go cause its best?😢