how to heal from your child's father when you have a newborn together

[LD233]

I'm really struggling mentally being in contact with my 6 week old babies dad. He did me so wrong. We were together and he cheated when I was pregnant and left me for his ex baby mom and they're still in a relationship now playing happy families together.
It kills me seeing him and I'm suffering with post natal depression . I feel like I'm stuck in a rut.
Can anyone give any tips or experienced similar to this because I don't know how to continue when I still have feelings for him and trying to heal from how much he's hurt me. I'm a first time mom and struggling but seeing him or speaking to him is making me so much worse. He comes round to see our son and everytime I break down - it's the hardest thing I've ever had to deal with

I want to say firstly I'm so sorry. I too am in a similar position and cannot believe this has happened. My baby is 2 weeks old. With 4 weeks to go, I found out my husband had slept with someone else and was still communicating with her. Since that revelation things just got worse and worse and he decided he wasn't in love with me anymore and thinks we should separate. So we are currently separated and he is living here still as obviously I am suffering now from depression and need the help with my baby. But it hurts so much to have him here. The pain is unbearable I know. When your life you were planning and dreaming of blows up in your face with no warning. Remember you are this babies number 1 parent right now and you need to make sure you are coping mentally. If saying no to some visits helps then you should.