Wedding without stepdaughter

My boyfriend and I have been a couple for two years. We want to get married this year. He has a 7-year-old daughter from a previous marriage. Unfortunately, her behavior in the last few months has been more than inappropriate. For example, she deliberately ruined his birthday a few weeks ago. We have her every other weekend and it is always challenging, nerve-wracking and energy-sapping. Today he said that he might not want her at our wedding. I'm afraid that he or she will blame me for this later. Right now he is emotionally really exhausted because of her.

UPDATE: i think i didnt make it clear enough - he has his daughter 40% the mother 60%, so not just 4 days a month. AND just 2 hours before he made the suggestion to not tell my SD bevause its not that importanz to her and wouldnt change her life…