FAKE FIL and girl

So long story short growing up my husband had a bad dad. He use to abuse him and even about had him murdered. He has changed but still isn't nice to my husband and has embarrassed him in public. We are now 25 we recently had a baby and when he found out we were pregnant said well I will worry about it when he born (we miscarried twice so this stung) fast forward to now. My husband cut out his dad from his life for 10 months our baby is now 5 months old. His dad just got engaged and suddenly wants something to do with his grandson and my husband. His fiancé has been bothering my husband about meeting my child and wants to know what she will be called idk her and we don't trust his dad. I feel like she has no idea about the past and thinks it's all my husband based on stuff she has posted on social media.. it just makes my blood boil that now he wants something to do with his grandson and suddenly now that he is getting married cares about seeing him and just now did something for him for the first time (bought t shirt). I know it's better than nothing but my child has 3 grandmothers already who have been there from day 1 I feel like it's all a show and so does my husband but he always wants to keep peace