After Giving Me Chlamydia, My Husband Is Now Making Passes at My Sister

hello laila
I will go straight to the point. My elder sister who has been living with us told me in confidence that my husband has been making passes at her. I knew something was amiss when i observed how disrespectful she suddenly became whenever my husbands talks to her. I tried to swallow it as hubby was not complaining , he was laughing it off, and considering that she was older and still single, I knew she depressed. She didn't tell me but I know how these things work. i thought she was just acting weird because she was unhappy. What got me more perplexed was that even though she turned rude to my husband, She respects me despite the fact that she is 3 yrs older than me. My husband always buys sharwama and ice cream for us on a daily basis but for some time now, my sister has refused to eat any thing he buys. I decided to sit her down for a heart to heart talk yesterday so I can encourage her that she will still find her own man and all. i didn't know i was in for something else

After talking to her and trying to encourage her and lift her spirit. She smiled and opened up, She confessed to me that ever since i gave birth to my second son which was over 5 months ago, that my husband has been making passes at her. telling her that he loves her and want to connect her to one of his friends for marriage on the condition that she will sleep with him. She told me that my husband stalks her, gropes her whenever he comes around her and even sneaks into the visitors room where she sleep whenever they are at home alone. I wasn't so surprised because I knew my dog of a husband can not be trusted when it comes to women but I was sad that even after womanizing outside, he still had the guts to bring it home and on my elder sister for Gods sake. My sister told me how helpless she was as she didn't want to tell me for fear of hurting my marriage and at the same time she dosnt have another place to stay and even if she did, she would have to explain to me why she wanted to pack out and she swore never to tell me but to persevere and see if she can raise money and get a room somewhere else. She believe that telling me may break my home

I understood her perfectly and after crying ourselves silly, I went about the evening chores as if nothing happened. Now I am deeply thinking of what best to do. I am not working and I cant fend for my kids alone. I need to get out of this marriage. This man has given me candida and chlamyedia before and i forgave him.God himself knows that i would have divorced this sick man a long time back but as it stand now I am stuck. When he came home last  night, I told him that i want to start a business. He refused telling me to concentrate on raising the kids for now. I don't know what else to do
My sister has no where else to go and I am stuck with this man without any money of my own. Please I need help