Hello, I'd like to assist you with your question. Thanks for your post tonight.
It's very understandable that you were hurt by all of this. Like you said the mother asked you to step up and be a father figure....but when it came time for a special birthday party you felt excluded and ignored.
More so it sounds like you were hurt, but your feelings were not taken into consideration. It may have helped a lot if she would have validated your feelings. Your emotions are not right or wrong, they are just that -feelings, we do not always know why we feel so deeply about something. It's very apparent you care a lot for this woman and her child- they are fortunate to have you in their life. A child can never have too many people care about and love them.
I would imagine having the father involved was uncomfortable for all of you. The mother may have been so focused on making it a "perfect" day for the child, trying to juggle, and balance it all, that she may have inadvertently overlooked your emotions. No matter what "shape" the child's biological father is in, it's natural for the mother to, on some level, to want that father in the child's life. Mothers feel deeply hurt by fathers who abandon their children, often causing that mother to cling to an opportunity for the father to get involved.
It may have been a whole lot more about the mother's emotional struggle with all of this, verses her intentions being to leave you out, to ignore, and hurt you. If the bio father is wanting to be in the child's life, while at the same time, the mother is wanting you to step up to be a father figure, that is confusing indeed. More important to consider is that you do have a special bond with the child, and that is separate from her relationship (or lack of), with the father.
The emotions you describe in response to this is normal- how uncomfortable to have the bio father there- may have felt like he was intruding on you and your family's space. The mother may have been really focused on keeping the peace, allowing the bio dad to get involved- she wanted to avoid conflict.
I hope you have had or will have the opportunity to share your feelings with her- explaining to her your feelings were hurt. She does not need to agree or disagree with how you feel, simply validate how you are feeling, to take your feelings into consideration- even after the fact. The more openly you can communicate with one another the better it is for the family.
We too often think we have to defend our self when someone shares their feelings with us, verses really listening and validating those emotions. I do not think the mother's intentions were to exclude, ignore, or hurt you, she had a lot to manage that day. You are a father figure to this child, the consistent one, it sounds like. The child will know and build a close relationship to the person, such as yourself, because of your involvement in her life. Being a father is something that forms with time spent together. The bond you have with the child is special, and it does not mean it will be broken if the father is also in her life. Sadly her father is not in her life as consistently, but having someone special such as you, can help ease the loss and hurt of that.
I hope the info was helpful. The best to you and your family. The child is very fortunate to have a "father" such as your self in her life- it's very apparent that you care a lot. Because you care so much for the mother and child, your emotions are more apt to get hurt when the "father" "shows up". The best to you! Thank you for your post.