Relationship failing and partner pregnant, im being pushed out?

She doesn't mean what she is saying or doing because pregnancy can make a woman act that way because of hormones. You say she has just came of citalopram which is also causing her weird behaviour. Try and live with her behaviour problems for a while because as the pregnancy goes on her hormones may settle and the withdrawal affects of her medication will ease. Pregnancy can cause a lot of mood swings and relationship break-ups but afterwards she can get back on her medication if needed and have a happy life with you and the kids. Don't do or say anything too irrational at the moment, give her time as she was a normal person before the pregnancy. Good Luck.