Parents’ Guest List Drama

My fiancé and I are having a relatively large wedding, and the guest list is getting a bit out of control. We’ve had to make some difficult cuts, and we are in the unfortunate spot where we are counting on a percentage of declines invitations. Despite the large size, we’d like to keep it as intimate as possible, only inviting those we have a relationship with. My parents have graciously offered to foot a percentage of the bill, but it won’t cover everything. They’ve received a number of guest invites, but my mother keeps expanding hers, and it’s beyond what we can allow. This is because my cousin, whom I’ve only seen twice (at funerals) in the past 25 years sent everyone a save the date to HIS wedding that is after mine. My mother has many siblings, and I o lot have a relationship with one aunt and cousin, whom I’m close with and are obviously invited. I wouldn’t even recognize the other siblings, and I’m not even sure what my married aunts’ last names even are. That’s how little I know them. Furthermore, many don’t get along with my mother, but my mother is VERY concerned with appearances and is making my life hell about inviting them. Inviting them would cost a few thousand dollars more because of the amount of siblings, spouses, etc., and we’d have to seriously cut down even more on people we want there. I don’t want to invite them, but my mother is emotionally and financially blackmailing me about it. In fact, on a related note, she has already made this entire wedding about her and has criticized and challenged every single decision we’ve made from my hair, dress, venue, ceremony, colors, suits, food, bridal party, and obviously guest list. Every time I make a decision that isn’t her choice, she takes it personally and tells me how I am “spoiling this for [her],” to the point that she has taken all joy out of it for ME and we’ve talked about calling it off. I think we’ve been courteous with the guest list invites for them, but we’ve drawn the line at inviting total strangers, blood or not, that I haven’t seen in decades and probably won’t see for decades to come. I conceded on some, and then she asked for more. I just don’t think it’ll ever be enough. Am I being selfish as she says, or should I stand my ground?