What to do about my childrens father

I want my childrens father to be a part of their lives but it’s super inconsistent and honestly my boyfriend (I’ve known him since kindergarten and have been dating for 6 months now) sees them more then he pretty much ever has. I’m doing the best for them that I can and my boyfriend treats them as his own. Any time I ask if hes going to see them I get I have to “work” or hes “sick” or someone in the house is “sick” he doesnt want to go through court for anything and basically tells people I dont allow him to see our children when I’ve caught him in multiple lies about working or being sick. I dont know what to do anymore, any suggestions would be appreciated! Thank you