I am so sorry your going through this, when you love someone so deeply it can be so hard to think about your needs first. I can’t give you answers, just advice because I don’t know you personally and can only go by what you have written but it does sound like your partner could be a bit emotionally manipulative and controlling.
(I’m not saying this to lay blame as sometimes people do this behavior without even knowing it, as it’s what they themselves have learnt).
But from personal experience, in a ‘healthy’ relationship you should never have to give up anything you own for your partner (eg car and job, the enjoyment of going out). I learnt this the hard way and realized I was giving him my power because of the lack of love and worthiness I had for my self and yes I thought I had good self esteem but when I had time away from him and to do some soul searching, I realized I was to scared to deal with my true emotions.
Based on what you have written, I would suggest if you have somewhere else to stay that you take a break from the relationship, even if you are pregnant. It will give you time to think and if you are pregnant be in a less stressful environment. However it only works if you cut all contact, including messages. You are so young so you don’t need to rush and make all your choices now. Maybe explain to him you need time apart to think, as it sounds like this relationship is making you a ‘different’ person from who you are normally.
I know it hurts to think of the children missing you but as harsh as it sounds, they are not your children/responsibility and you need to do whats best for you not them, so if that is whats holding you back from living in an unstable environment please remember everyone has there own path to teach them lessons in life and maybe there lessons are different from yours.

Please don’t think I’m just telling you to leave forever because only you can decide if this relationship is appropriate for you or not and maybe this will help your partner change his ways, but I suggest seeing a councillor (either just you or both) to help with the issues you are facing and a no contact break would be a good idea.

I truly hope you find your answer to this problem and the courage to make the right choices for you and of course happiness.