Step mommas. Need some support

After 5 years baby mama is now finally wanting a regular custody schedule. She promised to make it fair if my bf agreed to give up his overnights during the week. We have had 2 overnights durning the week and every other weekend due to BM request because she wanted to go out and party and f*ck around on her husband. That was the schedule since December until 3 weeks ago. So for the past 3 weeks we see daughter on tues and Thursdays but have to have her back by bed time. Well we just got the papers and she is going for full custody. Him only seeing daughter on tue and thurs from 5-8 and every other weekend and he has to pay half of all daughters expenses and have no say in it. Even tho he has never been asked to be involved in any of it. He has never gotten an insurance card so he can take her to dr appt. He has never been asked if it was ok for daughter to be in an activity scheduled during his time but has always been present and has always taken her. We struggle as he is still paying child support on what was asked of him when BM didnt have a job and she has a job that pays more than his for the past 9 months and she claims she still doesnt have enough. He has always paid his child support and has given money for medical expenses when he can. We suffer greatly money wise as i am the main provider off of a part time job( currently looking for full time)yes my bf has a job but his money goes towards bills and i provide food some gas money and outings with daughter and outings for just me and him for our date nights every oncein awhile. She is the type of girl to use the child against us and always has. She made the schedule when daughter was born and has changed it to her liking so she could go out. Its upsetting to see such a dramatic change in daughter behavior since her mom took away our overnights durning the week. She used to be a well behaved child few tantrums now everytime she comes over she is screaming her head off asking when her mom is coming for her. Of course her mom never comes we always have to drop her off and see the sad in her eyes when she realizes her mom isnt home when we drop her off. I cant believe this woman would consider taking her away from a stable environment that we have given her to have her when BM is never there to take care of her or acknowledge her. Bf is planning on fighting this and going for 50/50 as they live in the same city maybe 5 min away from each other. I know im technically not a step mom but we are engaged and daughter has been in my life since she was 6 months old so she is my daughter as far as im concerned. I just have had a hard time dealing with less time with her i feel sad that we cant put her to bed like we used to and i feel like im missing her all the time. How do i cope with this without taking my feelings out on my bf?