How to deal with my son father(my ex)

Alisha
I have a 3 year old son with my ex bf, we were together for 2 1/2 years. He was few years older than me thought it was gonna last but I felt unhappy for a while. He had no job half the time, I was the one that had the same job for 3 years. He always put me down on things. So I left him a year ago and he made my life a living hell saying I was never a mother to our son, never was around and he always asks me for money for child support when there was no court at the time. I was around for my son I was the one to support our son. I didn't have family to just fall back on when we broke up like he did. So I was very Invole with my son life. One time my ex refused me to see my son for two weeks cuz I didn't give him money I told him I'll pay for what ever he needs but I'm not giving you money so you can spend it on whatever you want it's for our son. He didn't like that answer. It's gotten little better now we went to court finally and we both got 50/50 with our son. But now I'm married and having twins with my husband my ex thinks I'm going to forget about my son and be more foucs on the twins than my first born.which isn't true. I know it will be tough raising three kids but I know I can do it. Just hate how my ex puts me down all the time acting like I don't know how to raise our son. I just don't know how to deal with my ex.... Any ideas ?