I have two girls. I was pregnant and single too, so I've been where you are. My girls are 3 years and 17 months. I was resentful towards my ex for a while, he has issues and claimed to be fixing his life now! Great for him 2 years too late, lives in a different country now and all for a new girlfriend.
Tip:1 Anyway, I cope by being active. Staying in the house can drive you to insanity, the littles get soo bored and you'll get depressed. My oldest is at pre school and in that time I try to get out with my youngest. On weekends I've just started searching for soft plays, free museums with kids areas and anything free or cheap. It's helped me enjoy the children's youth too.
My oldest asked for her dad too, because his been in and out of their life's. I just explain in a kid friendly way that daddy lives elsewhere, for now.
Tip 2: Get organised,because it will coz less stress later on. Finances etc get a little savings accounts because on of the biggest stressors is money, even if you put £5 a month, you never know when it might come in handy. I'm trying this 52 week money challenge, basically week 1 you put £1, weeks two you put £2 and so on.
Tip 3: Get a little support network, just a few friends you can talk to, even better if you have a mum or grandma who can look after little out for time to time. If someone offers to get you a break for a few hours,take it, most of us only get them once in a blue moon.
Tip 4: Try not to war with dad. This one can be hurt because a lot of men don't get how hard. Seeing him care free and not bothered about your babies might bug you.True me, it's not worth the headache. If he wants to be involved let him,but limit your contact to just kid talk etc and if he doesn't want to be involved don't force it.
And lastly don't forget about you, as mums we do focus so much on the kids we forget to take care of us.