Im so sorry you are going through this. It does sound like postpartum depression.
Please make an appointment with your doctor as soon as you can. They will be able to give you a definite diagnosis. There are several medications that you CAN take for depression/anxiety disorders that are considered safe while breastfeeding. Counseling may also be beneficial but based on your medical history medication may be warranted to get you over the hump. PPD can last up to a year so seek medical advice as soon as you can with this to take care of this sooner rather than later.
I hope you feel better soon and this is NOT your fault - it is a medical condition that you have no control over. Just as a diabetic would seek medical treatment for this disease, someone with PPD should seek similar treatment for this medical condition.
The first step is definitely telling your doctor so that they can help you deal with the depression.
I also want to add that a new baby puts major strains on relationships and that you guys both need to readjust to your new lives, with a baby! But first the mental/emotional issues must be dealt with via your doctor.
you really need to let your doctor know about this. She/he will probably want to put you on meds if you are not on them right now or change your meds if you are. You might want to see a councilor too. It may help. Have you sat down to talk to your spouce about this?
I have depression and anxiety problems and at certain points feel I don't need meds so don't take them (or for certain reasons can't take them, like right now I was told not to because of my pregnancy and am having problems with the depression and anxiety) then for no real reason at all a year, a few months, or whatever down the road, I will just start getting real bad again. When I do get real bad Jaison knows that I suffer from this and will do what he can do deal with me when I am ranting and raving about nothing at all. Small things just irritate me soo bad when my depression and anxiety get bad and I will start fights with Jaison over something stupid. I also feel tired and achey when it gets bad and will really not do much at all but lay around. THat upsets him because I just lay around like a lazy leach. He just tries to stay calm and deal with me. He knows it's hard on me. We have talked about it and he understands now what the signs are for me and that I do not act that way just because I'm a b i t c h or whatever. If he has a real hard time trying to work with me on it he will tell me he thinks I need to go to the doctor and get back on meds or to go see a councilor. When my depression does get real bad I will go to a councilor. It helps to be able to talk to someone about everything, even the things I feel I can't talk to Jaison about. It wasn't always like that. We would fight like cats and dogs until we worked it out and I told him about my problem. I even have a councilor now who knows he may at one point not see me for a year or half a year at a time when I am doing well and Jaison is alowed to call him and talk to him about how I'm doing, with my permission of course. But certain things I would like Jaison to know about but feel uncomfortable talking to him directly about it. I'm a shy person.
ANyway, Try sitting down with your husband and talking to him about the problems you are having and I would recommend going to a councilor. Even if it's short time to get things off your chest. Depression can be a pretty serious thing. It can get real severe to the point that you may hurt someone or think about hurting someone physically. You need to speak with someone about it and get on some meds, even if you feel bad that you won't be able to breastfeed. If your husband understands what you are going through it would make it a little easier. He could have developed depression also after baby was born also, try to get him to talk to you about how he's feeling. Men can get some form of post partum depression, it's not called that for guys, but I was told to look for signs of it in Jaison since our last son died he might have problems getting close to baby or adjusting to baby and could even not want baby around once it gets here out of fear of losing him. Talk to your husband it really might be all you need is to understand each other.
megmil has an excellent point - have you discussed this with your husband? Tell him exactly how you have been feeling and that PPD might (very, very, very likely is) be the cause. Direct him to some websites.
Of course, see your doctor ASAP to get help.