Help please, feeling lost and stuck :(

Let me just preface by asking please no judgements on what I'm about to write - believe me I am already judging myself more than enough, I feel like I've made numerous wrong decisions and an living in a world of regret.

Bit of background - I have a 6 year old son and am currently 22 weeks pregnant with my 2nd child. I am no longer with my son's father, we split when he was 3 years old. I feel like there's 2 stories here so I'll start with my son's father...

We were together for nearly 7 years, engaged and had suffered multiple miscarriages after my first. I split up from him as for a lot of the relationship he was mentally abusive and threatening to me whilst he was drunk. It was such a hard decision as sober he was great, and a really good dad and I did still have feelings for him. My problem was that even though it had been a good 6 months since anything had happened (abuse) and he had realised his wrong doings, I was suffering from depression and anxiety as a result of it all and I just couldn't get out of my cloud enough to have the strength to stay. 3 months after we broke up he met someone else and that settles down really quickly. I was not ready for another relationship for some time, I was more focused on working on myself and taking the time I needed to get better.

My current partner: (father of my unborn child) I met about 18 months ago and we hit if off straight away. I was so happy at the start and in a way I think he helped me recover from my issues and I no longer need any medication for my depression. It was like the cloud had been lifted. He moved in after only 3 months which looking back now was probably too soon. 6 months ago we decided we wanted to have a baby and it happened pretty much straight away. My current problem with him is that I'm starting to realise he's not the person he was when we met - whether I was just blinded by it or hes changed I don't know. But he's lazy, can be quite rude, arrogant and blunt to everyone but me which is a quality I am not at all attracted to, he doesn't really pull his weight around the house but happy to leave his filth for me to clean. I'm getting less attracted to him as his personal hygiene isn't up to scratch - he rarely brushes his teeth which I find disgusting but don't know how to bring it up to him.

Back to my ex (son's father): He recently broke up with his new partner. I wasn't expecting it, I thought they were settled, especially since they bought a house together a year ago. I'm feeling so torn as all these old feelings are coming rushing back to me. I know that if they had broken up 7 months ago I probably wouldn't have made the decision to try for a baby with my new partner. I can't get this yearning out of my head, of wanting to be back with him and put our family back together now we have both grown, had time apart and sorted out our issues. But I'm feeling stuck as now I have this new life growing inside of me to think of, who is to a different person and it makes me feel SO guilty that I've selfishly made the decision to bring this little person into the world. If I leave my current partner not only will I hurt him, I feel it would be hurting my baby also, to rob him or her of the opportunity to have a proper family. But if I stay with him, I'll always have this constant what if in my mind, I don't want to end up miserable and resentful. I know this all sounds horrible, I know I've made not the smartest decisions I don't even know exactly what I'm asking of all you mummies, I guess just some insight from others would be good, or if anyone has been in a similar situation and made it work I;d love to hear.