I am so terribly sorry for what happened to you. I’m also sorry for the shabby way she decided to approach you about this.

No one deserves to be dealt with this way but I suppose it was better than her just taking off without telling you anything.
She said she did this to give you time to think? Well, wasn’t that nice of her! She didn’t even want to stick around and talk this thing out?

Years ago, I was seeing this guy who was a supervisor at a local steel mill. Foreign steel was being dumped on US markets for a cheap price, meaning that the American steel industry was decimated. Layoffs began en masse and he was one of them let go (last hired, you know). Without any warning he broke it off with me. I made certain we never did anything expensive when we were together (I didn’t want him to think I saw him only as a paycheck). I don’t remember how he broke it off with me but I reminded him that our time together was as inexpensive as possible. He never gave me a reason—he wouldn’t answer the question. If I wanted to see him it would be on his terms only. I figuratively walked away and never looked back. It’s not like I didn’t cry because I did, but time had to pass before I felt better.
You’re very big-hearted to accept the fact that she cheated on you at least once (the pregnancy). I’m a woman and can be extremely hard on other women for things they’ve done to a man.
Right now your nerves are very raw—I’ll bet you go from catatonia to feeling deep hurt and betrayal.

Emotional breaks are like physical breaks (as in a broken arm), they take time to heal. However, I think the process is a little more draining because all you can focus on is what she did to you.
I don’t remember when you said she was coming back to move out but if that hasn’t happened yet:
1. Look over the instrument you signed on the house. If you’re renting and you’re locked into a block of time (renew every year, not on a month-to-month basis) with a penalty for breaking a lease early, there must be a decision made on how the penalty will be settled. I’m assuming you plan on getting out of there as soon as you can.
If you’ve actually purchased the house and you can’t afford the mortgage that gets trickier. You may want to seek legal assistance on how to handle that. If she won’t take responsibility for her financial obligations you must make her, even it means Small Claims Court. Don’t you dare let yourself be left holding the bag for things she skipped out on.
I know it sounds terribly cold and analytical but, depending on what she wrote you, she may have been planning this exit for awhile. You need to protect yourself this way—you don’t want your credit score ruined because of this.
What else to do?
a. Mourn your loss. It’s OK to cry, to get angry, to rage at the Fates. You’re going to be on an emotional rollercoaster for awhile. Right now you may still love her, but why? It could be because you don’t want to be alone. Do you deserve to be treated the way she treated you? I think not.
I was in a relationship for over four years with my First Love. When it was good it was GREAT, when it was bad it was HORRIBLE. Whenever there was an argument it was always my fault and he had me so convinced I was a bad person that I went to a psychiatrist when I was in college to find out why I was so bad. I thought that since he loved me he wanted only the best for me and if he said I was a bad person I must have been. I finally realized that I wasn’t the bad person I believed I was and I knew at some point the relationship had to end. When it did end, I was still devastated and it took me at least six months to get over it. I cried, I quit eating, I lost sleep. When I did sleep I’d have dreams about him and would wake up in a cold sweat.
I was very fortunate to have a group of friends (male and female) who ended up being my support network. They were extremely understanding and sympathetic. Without them, I don’t think I could have made it through the healing process. So:
b. Time to spend time with friends and family who will lend you a shoulder to cry on. They may be able to help you pick through the pieces of the relationship and see if there were warning signs that you might not have seen. They’re also very good at sharing their experiences and may give you insight.
HOWEVER…
If you have mutual friends it might be a good time to stay away from them for awhile. It’s too easy to end up in a conversation about “her”, and that’s the last thing you need to hear right now. If you happen upon them and they bring up something about “her”, change the subject. If they don’t take the hint, be a little more direct. If that doesn’t do it, then politely excuse yourself.
c. If you get invitations to go places (even to a movie or the mall), TAKE THEM. You may not feel like going but you need to get away from your unhappiness for awhile. You’d be surprised how good you can feel (even it only lasts a few minutes), and will realize that things will get better.
d. Is there something you’ve always wanted to do? Now’s the time to take up a new hobby or join a new group. If you don’t go to a gym or the Y, consider doing that. Volunteering time is also a good way to help yourself heal. You need something in your life to fill up that empty time and make you feel good about yourself. You’ll meet people who have at least one shared interest with you and can develop new friendships.
e. I kept a journal whilst I was going through this and it helped me immensely. I could pour out all my feelings into it and could say thing over and over again (“why did he do this to me?”) without sounding like a broken record to my friends. It’s a good way to help you see how you are healing.
f. Try and take joy in just one thing every day—a sunrise, the breeze, the way the dogs greet you when you get home. It doesn’t have to be something great, but if you can see the beauty in little things you know that better days are coming.
Everyone heals at his/her own pace but by keeping occupied and setting goals for yourself you’ll heal faster and healthier than shutting yourself off from everyone. You’ve learned some important lessons from this relationship and you’ll find out what they were as you heal. I learned that I am a person of worth and should not have let him manipulate me. I realized he was insecure and jealous and I wasn’t the wicked person I believed I was.
I hope this helps. Please feel free to pm me if you need a virtual shoulder to cry on.