It's a good thing that you've asked for God's forgiveness for what you've done and you had also released forgiveness to yourself, too. Been there, done that.
But focusing on the matter at hand which is the treatment of your MIL to you, regardless kung nabuntis ka man o hindi before marriage, kung ganon talaga ugali nya, ganon talaga sya. Kaya mahirap na makitira sa in-laws. Darating talaga sa puntong may makikita at makikita sila sayong hindi maganda. Lalo na kung feeling nila, nagiging burden ka sa kanila.
You better open up sa partner mo para malaman mo rin kung kaninong side sya. I mean, hindi naman sa dapat pumanig sya sayo but at least I think with that (opening to him your situation/relationship with his mom) malalaman mo how he decides, how he thinks. With that, mas marerealize mo kung dapat mo syang pakasalan or not.
But nevertheless, do not stress yourself too much for your baby's sake. Pagpray mo rin yung MIL mo. We cannot change people, only God can. Faithing!
Ma. Benelda Timbang-Obogne