Ok, I lived in apartments for years, both before having my son and as a parent, so I know what you're going through. I see a lot of people saying 'just move!' but I understand that if you break your lease, you forfeit your deposit and it may not be so simple to find a good place that is convenient to where you go to school, babysitter, etc. So, assuming that you moving is not an option- This is what I would do:
1) Get the other tenants in the building to act WITH you, if possible. I know a lot of people would rather just complain and not do anything, but if you all stick together you have a lot more push, both with the neighbor, with the management office AND with the cops. Stand together- that makes it harder for officials to ignore you and it also makes it harder for these jerks to retaliate against you- they can't go after everyone in the complex. Explain to them that you are taking this to the building management and ask them to sign a petition. That way you don't just look like a crank or a whiner. Look up Illinois Tenants' Rights online and that should give you some guidelines as well.
2)Go talk directly to the building management. If possible, take one or two other neighbors with you, so that you are a group. Is your building owned by an individual or a manangement company? If it is a company, get their actual office address, not just that of the complex manager on-site.
Put all your complaints ( along with dates, times, when police were called, etc. IN WRITING and mail it to them, as well as going there to talk to someone yourselves. Whoever owns the property can face legal charges if they continue to allow illegal activity to go on there.
Be polite, but firm and make out a list of everything you are complaining about. Give them the list and tell them that the ENTIRE building (they won't know if it is true or not) is committed to getting them to clean up their behavior.
Tell them that the neighborhood watch will be calling the police and documenting it anytime there is partying, smoking up, being loud or doing something illeagal. Let them know that the neighbors- ALL of them- have had it with these problems and that the building has become unsafe- make sure you mention the guy pushing your kid. I can't imagine any management company wanting to be held responsible for something like that happening on their property.
3)This is hard but- you and whatever neighbors you can get with you- MUST call the cops whenever stuff happens. You need to be able to show both the management and the police a built up history of incidents for it to be enough for them to do anything about it.
I would also recommend going to the police station and making an appointment to speak to someone about how to handle the situation. Again, if you can get neighbors to go with you as a group, that would be best. But what you want to do is make sure that the cops know who YOU are and see you as a nice mom who is just worried for her kids and who really wants her apartment building to be safe. Explain to them about the retaliation that has happened since the previous officer told the other tenants who called the police. Get the name and number of a community liason officer or whatever they have there ( that was what it was called in Chicago) and USE THE NUMBER. Make sure they know how serious you and your neighbors are about this, and that you are trying to get the management to move these clowns out of your building.
The last resort is to get a group of neighbors together and formally write to the owners of the building and withhold your rent until the problem is taken care of. Eviction is a long and difficult process for owners and they probably don't want to have to throw these guys out if they are paying their rent. But if enough OTHER units threaten to withhold rent over these problems, it becomes worth their while to evict the other guy. Make sure you put it IN WRITING- everything- along with the specific incidents, police calls, etc.
Sorry this is so awful for you! Do some groundwork with your neighbors, the office and the police and get them to throw these guys out! A lot of apartment complexes these days, no one knows anyone else and people keep to themselves. But it is better for EVERYONE if you all keep in touch with each other and look out for your neighbors! I hope they see this- good luck!! Make sure you let me know what happens!