You've already done one of the most difficult things, which is kicking him out. I'm so proud of you for taking that huge and scary step; it's very brave and you should consider yourself one step closer to healing, even though you're still feeling stuck in the thick of it.
I echo the other references to document everything, literally, just as the other commenter said. Calling the police for anything is also another excellent step to take in documenting the abuse and his harassment. Do you think you hear someone outside? Call the police. Even if it isn't him, it will show the courts that you have been afraid and he is the source for your fear. If he is following you, if he's lurking around your son's school, ...anything, calling the police gives the court more proof in your favor.
Talking with a local women's shelter may also be a good idea. Use caution because sometimes women's shelters are excellent sources of aid and other times they're not. Talking with a counselor would also be helpful. Some shelters and non-profit abuse relief centers offer classes to help abuse survivors overcome abuse and learn tools to prevent themselves from entering unhealthy relationships in the future. That may also be helpful and encouraging to you.
I didn't notice if you mentioned if this man is was a boyfriend or husband. If he was only a boyfriend, he does not have automatic parenting rights. If you were not married, he'll have to request and pay for a paternity test if he wants parental rights/involvement. Also, in most states (maybe all) parenting time and child support are two different things, meaning: just because he has to pay child support does not mean he may also be granted parenting time. In your case, I would request supervision from CPC for the safety of your children. If you're planning to breastfeed, it will be years before he is allowed to have more than two hours of parenting time with your infant. IF he gets any time at all. Request family or friends to also document information and attend court with you to show support for your case and emotional support.
Also, is this man also the father of your older child? If not, and you're not married, is anything stopping you from moving and changing your name? Would he try to find you? Or is he already moving on to another woman?
I'm sorry for what you're going through. I've several years out of an abusive relationship and while I have healed a lot..some days are still difficult. I still cry some days. I still feel afraid some days. It does get better though. You have your life and two lives to protect and raise. That is something to be thankful for. :) I read the Psalms a lot. The three I find most comforting on the days when I feel defeated is Psalm 3-, 31, and 32. If you believe in God and His word, they're certainly worth a read. :)
Thinking of you and praying for peace and healing.
Follow Mothering