It sounds like the first big issue is your own self-esteem. You lack confidence in yourself. This won't be helped just by losing the baby weight. You have to truly love yourself as you are, and trust that you're good enough, pretty enough and worth enough to deserve love. I think the first step will be working on boosting your self-esteem. Outside of professional counselling, you might find it helpful to volunteer. Doing good for others helps us feel good about ourselves. Also, seek out challenges and learn something new. Once you feel better about yourself, you'll be better able to focus on relationships.
Secondly, you need to make it clear to your boyfriend that you will not tolerate him watching this pornography. You don't owe him an explanation about your feelings, just make your expectation clear. He already knew you were upset before, so don't waste breath telling him why again. Let him know if this continues, you'll be leaving because you deserve a man who respects you. Then, if it continues to happen, follow through and leave. I'd also suggest ending the friendship with the porn star. Clearly, comparing yourself to this person causes you a lot of unnecessary anxiety and upset. In the meantime, make arrangements in case you need to raise your child on your own.
I personally don’t feel I can say what I would do in your situation because it is such a gray area. But if he knew how much it bothered you the first time and he continued to look at her porn specifically, I just feel like it’s kind of horrible to look at how much you’ve hurt your significant other and have it in you to do it again knowing it makes them cry for days. Especially given that you’re being realistic in saying porn is okay but not my friend that’s not unreasonable. You made your boundaries clear and he broke them. Is it a reason to break up? Only you can decide that, I personally wouldn’t because I feel like it’s such a small thing comparatively and it sounds like he’s a good partner otherwise. Be careful with ultimatums such as threatening to leave as a way to get what you want, or prove how hurt you are that can be very damaging. Maybe try rephrasing your needs to make it less defensive and critical but still clear in what you feel and need.
I didn't realize you've already told him you prefer he not look at it. That stinks. That's disrespectful to you. Does he realize the extent of your feelings? That you are thinking of leaving him? I wonder if this would change his mind. And I'd be done with the friend. too much weirdness if you are all together in a room again. Sorry this happened.
The other thing is, you are now responsible for another life, your child's life. Kids do best when their parents are together. How could you anticipate telling your child as he was growing up that the cause of you breaking off with his dad was that he looked at a porn flick that had someone you knew in it, and you went into a tizz because it made you feel like you didn't look like a porn star? Wouldn't you feel like that was ruining your child's life for very little?
Argh, it's hard to have a problem with porn If you are cool with a best friend making the porn. I'd not really want to remain close to the friend due to her lifestyle choices. Or at least beg her to get help and not degrade herself that way. I guess it is awkward to think of your man watching your friend being sexual. I'd not like that either and of course it will be on his mind when he sees her. BUT, he's the father of your child. Have you chatted with him about your feelings? Have you told him this bothers you? What's the rule on porn in your relationship? You say you are okay with it in general but it's kind of not fair to say not your friend's porn unless you told him. And now you have to have the awkward conversation of how it made you feel . . . but I'd do it to clear the air. Don't be insecure, hon. He is with YOU and has a baby with YOU and that is meaningful. Having a hot friend . . . well, we have to just get past that.
Although, I personally would back off from the friendship until she gets things turned around for herself. I had a friend who dated a married man. I didn't hang out with her or stay in touch with her for about 3 years until it was all over. I just have my boundaries and it made me too uncomfortable. If this makes you uncomfortable especially now that your boyfriend has seen her 'work', I'd just back off from her. That's just my opinion. Letting go of people is okay when it makes our life more peaceful (emotionally speaking). good luck
Also I know he watches regular porn and that doesn't bother me at all because it's not someone he knows