how am i supposed to feel?

so back when i was pregnant with my daughter my now fiancée and father of my children and i broke up and he got with another woman. they were only together for about a month until we got back together but the day i went into labor she found out she was pregnant with his child. she had no contact with him throughout the pregnancy only though his mother. about a week ago his son was born and they’re back on speaking terms but around the time she had him i found out i was expecting our second child. we finally went to meet his son today and i don’t know how to feel. i was very pissed off at first and my feelings were hurt but now i’m just confused. i’m glad that he has a relationship with his son but he went out and bought him stuff at the store which i’m glad he did but he never did that for your daughter when she was first born. there’s a lot of things he’s done for his son that he didn’t do for our daughter when she was that little and honestly it hurts my feelings. i want to be a good step mom and love this child but it feels like he’s going to be a constant reminder of what happened. he was upset when we found out we were having a girl for our first and now that he’s got a boy that wasn’t from me i just don’t know how to feel towards the situation. i’ve been struggling with it since we found out she was pregnant