because you two are not married i would suggest writing up a parenting plan and both of you need to have it notarized then file it with the courts. No lawyers or mediator needed, especially if you two can be civil and able to come to mutual agreements that are in the best interest of your two kids together.
be sure to stipulate how to separate holidays, birthdays and special occasions. How you want to split the time 50/50 each week. Then you need to state their time during school breaks, summer vacations, parents birthdays. Write as much as you can down, Also in your parenting agreement, be sure to state in there if either one of your schedules change or work, or even residence changes that a new written agreement must be done, again notarized and filed with the courts.
make things simple stupid. I have full physical custody w. joint legal. Our visitation schedule every other weekend he see's his dad. Starting saturday morning till sunday evening. We live 2hrs away, so i handle everything without fathers assistance, but thats by his choice.
Odd years are mine for holidays, except my birthday or my ex's. Son bday is generally with me because it always falls on a week day. Holidays since we moved have been hard, especially during the week. I cant afford to take time off, so he's been with me, except for thanksgiving and christmas, i take time off so dad can see him.
you will have to agree with what is best for everyone involved. Be sure to address once both of you have a relationship, that a new partner must NOT interfere with things are. Both agree to support the children financially. Help out with childcare, medical, etc. THink of EVERYTHING to cover yourself for later issues.
by the sounds of it, i hope you two can continue being adults and awesome parents for your children through this break up. TOo many kids are effected due to the immaturity of the parents during times like these. As they forget its not about them, its about the children.
Push come to shove, if it gets ugly, and i pray it never does, you will then have to consult an attorney. Until that time...continue being civil and supportive friends and parents :)
good luck