My Sister-in-law is Frustrating our Reconciliation!

Good day ma'am, I have been an ardent follower of this page and I must confess that you are a divine project of God. Ma please I have an issue and I need urgent advice from you and that of your fans. Am married for four years now, and I have a baby boy of three years, during courtship there was no sex cos we both agreed. I took in the same month I did my traditional marriage and the whole story changed.
When we came back to our base, my husband insisted we go pay homage to the elder sister for attending our traditional marriage, and since then the sister is the one running the affairs of my marriage. She will either call my husband to know how am behaving, to the extent that when she heard am pregnant she asked the brother if he was sure that he was the one that got me pregnant. After two months of my pregnancy, we moved to his sister's house, with heavy pregnancy, l was subdued under her. l did all the house chores without complaints.
Aunty  to cut the long story short, when I put to bed my baby was one week old and my husband started keeping late night, atimes he comes home by 12 midnight with all sorts of smell of Indian hemp and drink, and will make trouble with my elder sister that came to look after me and the baby that she should go, that he is not comfortable with her, my sister left and he started bringing girls in.
At a point he invited one of his girlfriends from Onitsha to the house and she spent days in our house, doing everything together with my husband and I was left behind. Out of anger I laid allegations on my husband that him and his girlfriend wanted to kidnap my baby and sell, and her sister locked him up in the police cell but he was released the next morning and we separated for two years.
Now, my husband is calling, pleading that I should come back to the house but my sister-in-law said over her dead body, that I must go and bring my people for her to insult them, and after that, she will give me condition which is that l will have to go to her church for deliverance that am possessed, before I will come to her father's compound.
My husband told her that he doesn't need this condition to bring me back that what happened between us was contributed negligence. Aunty what have I done wrong? My husband is sacred of his sister, that he can not go contrary to her words. l don't know what to do, and I don't want to put my son's future in a jeopardy, if l choose not to go back.


Whether you decide to go back or not, you can still give your son the very best in life with or without your husband. All you need to do is humble yourself and work hard to give your son the very best that you can afford irrespective of how your marriage turns out. 
From all you wrote, it's obvious that your sister-in-law is manipulating and controlling your husband, and your husband isn't emotionally prepared and psychologically mature for the responsibilities and the challenges that comes with marriage. 
He can't make any decision without his sister's permission and that is why you are where you are today because he's afraid to be a man who can stand on his feet and work hard to earn a living and take care of his family and children. 
If he's serious about you coming back to him, first he must leave his sister's accommodation and rent an apartment for you and your son even if it be the cheapest of them all, as long as you are not under the command of any of his relatives, it's a huge difference. 
Secondly, he must learn to work with you and shun his sister. Any man who always reports his wife to his family at any slightest issue is a coward, immature and childish for marriage. He must be fit to manage issues and deal with them with his wife without reporting her and exposing her to the ridicule of her in-laws. It's simply inappropriate for your in-law to query your husband about your pregnancy and who was responsible for it. 
Thirdly, he must decide not to cheat on you or have the thought of bringing a strange lady into your matrimonial home. Where is such done please? He must realise that he did something that was a taboo and a horrible thing in the eyes of God and men. Let him respect your privacy and your body, that's what makes you his wife and not a strange lady. 
And finally both of you must agree on a place of worship where your spiritual life can be nurtured and nourished by the word of God and prayers. You don't expect your marriage to prosper when you don't seek the face of God on a daily basis over your husband and your son. When both of you pray together, worship God together and encourage one another in the word of God, there must be a great difference in your marriage and both of you shall have reasons to enjoy your marriage. 
If he's not willing to make this very important structural adjustments, I won't encourage you to return back to his sister's prison to avoid being used as a slave in the name of marriage.