Time cures all if you allow it to. I know it sounds cheesy and cliche, but it's true, nonetheless.
For you guys trying to see your kids, and the ex is interfering..... YOU GUYS HAVE RIGHTS!!!!!
You (more often than not) do NOT need an attorney. They just usually bleed you dry (but there are some good ones) All the info you need can be readily found in the library of your county courthouse
What you need is (on average) $20 for the prothonotary at the county courthouse where you live for the fee to file a Petition for Custody.
There is legal custody (choice of religion, education, etc) which you should file for shared custody, and physical custody (who has the kids) for which you should file partial custody. From what I can tell, the average seems to be every other weekend and one weeknight. Unless you have some SERIOUS skeletons in the closet (and usually this must be proven with documentation) there is not a court in the land that will deny you from seeing your children. The ruling will be ALWAYS be based on what is "In the best interest of the children (as phrase that you will hear over and over) Children being able to see both of their parents (barring the aforementioned skeletons) is always in their best interests. Once you have that custody agreement, in writing, signed by a judge, it is a Court Order.
Once you have a court order giving you the right to see your kids, any funny business on your ex's part that interferes with you exercising that right, becomes contempt of court. End of story. When this happens, you document it. Keep a notebook, call the cops when you show up and she has decided to take a trip, keep your custody papers on you, videotape your arrival (time and date stamp, of course) whatever you need to do to show (and prove) that this is happening.
Standing tall before a county judge for failing to comply with a court order will change the ex's tune very quickly. And (around here at least, and I can't imagine it's much different anywhere else) judges ARE NOT AMUSED when folks do not adhere to the terms of a written order that they have passed down.
I have seen it happen (not in my case because thankfully my ex stopped that nonsense when we had a written agreement), but I have seen judges come down on others while waiting for our case to be heard, and it was not pretty.