Really good question, looking back I would not change a thing. . but as far as advise goes well . . . .
You are not alone as their is a huge support network out there in family and friends, dont be ashamed to ask or feel people will judge you for asking. Easier said than done but it does get easier as time goes by and a routine develops. Just because it feels the other parent doesnt care about the children it doesnt meen they are missing out because you can get a balance in what is best for the children and be their 100% as it is them that matter, regardless of arguments and disagreements its not the childrens fault so although out of your control they should not be caught in the middle of it.
You can do this and although the hardest job you have ever had it is and will be the most rewarding. .