How do you know that for certain? You can't predict the future. It sounds more like you are falling into the negative thinking again only this time you are projecting the worst that could possibly happen. If the OW is pregnant the only thing that really means is that she will have a baby. It doesn't mean your h won't return to you if what he sees in you is better than the OW. But, that's the clincher, isn't it? Are you making yourself look more desirable than her? Are you showing him he's making a huge mistake by leaving when he would be losing a great woman?
So far, it doesn't sound like it from your posts. Because you don't believe that of yourself. You have believed the lies of negativity and are wallowing in it. I am not being critical of you, because I've been there myself! And occasionally I slip back into my own pity party.....I just learned not to dwell there. You know why? Because it's EXHAUSTING!!! And what does all that get you in the end? ABSOLUTELY NOTHING!!!! You then are so depressed you can't stand yourself, let alone anyone else wanting to be around you. You might have given yourself a headache, upset stomach, etc. And the atmosphere around you is awful! How do I know this? Because I've done it to myself.
You have a choice. Continue to be a miserable person who wants to strike out at everyone, or suck it up, put one foot in front of the other and decide that for the next 10 minutes you are going to be positive. And after that 10 minutes is over, make your goal for another 10 minutes, etc. You can do this! And the next time you want to be negative, keep it brief and keep it to yourself. Have you ever heard the phrase "garbage in, garbage out?" Well, it applies to you big time! You hear the words that come out of your mouth and you start to believe it. You dwell on those. So, stop it with the stinking thinking! If a negative thought comes into your mind, tell yourself you refuse to believe that anymore. Say positive words out loud... you are a strong person, you can handle this, you are determined to make it, etc. Of course you will feel like you're lying to yourself.....we all feel that way.
I have a book to recommend to you. I have read it and I keep reading it over and over again when I fall into that negative line of thinking again. It's Battlefield of the Mind by Joyce Meyer. It's excellent and it fits your situation perfectly. We are responsible for what we believe and how we react. You can't force your husband to act a certain way. But, you can change your way of thinking. If you really want your husband to come back to you....give him a reason to. You would have never attracted him to you in the first place by acting the way you have been. I confess that after reading your posts, I have come to believe he didn't leave....he escaped. Become the woman he wants to come home to. And if that doesn't happen.....you will be a strong, independent woman who he will look back on and realize he royally messed up.
By the way, I don't care how depressed you are.....do not act that way around your son. I'm sure he's a bright boy and understands more than you think he does. Put all of your attention on making yourself better and making the life with your son the best ever. He is your priority now, not your husband. Remember, our kids watch what we do. You are teaching him a lot just by your actions. I'm sure you are a good mother....but your example has not been the best towards him. You can do better....we all can. Fake it until you make it!