Medication like Antidepressants (SSRI – Selective Serotonin Reuptake Inhibitor) helps to boost Serotonin level.

But there are natural ways to do it without medication. There’s this strange herb called “St John’s Wort” – it is said to be more effective than Prozac. No, it is not for mild depression only and ignore those sayings. In fact, it does help anxiety and panic-attacks as St John’s Wort works like prozac. Other natural ways will be exercise, diet, more exposure to light, etc.
The problem is that, even if your Serotonin is balanced… you have that “learned behavior” in your mind. You need to break that initial cycle to destroy that learned behavior – Cognitive Behavior Therapy (CBT) does this. A technique that you can use without CBT will be Distraction… There are several other techniques to help cope them!
Ok, to use Distraction: Firstly, try to….

Extracted from Source.

But it sounds like the price you guys paid and the house’s real value, whatever the heck that means, is not the issue here. The issue is your husband’s inability to tune his mom out and ignore her.

You CAN’T get your MIL to understand anything that she doesn’t want to understand. The only person whose actions you can control is yourself. Why are you letting MIL bug you? Can’t you just treat what she says as background noise and enjoy your new house?

If she’s really bothering you, why don’t you take the bull by the horns, and instead of trying to convince her that you didn’t overpay, your home is on the right size acreage, etc., etc., confront her directly and ask her why she is hell-bent on believing that you and your husband screwed up: “Mom-in-law, do you WANT us to have overpaid? Does believing we’re doing this all wrong make you feel good, somehow? Is it necessary for you to make [your husband's name] feel bad about what we did because it’s not what you would have done? Okay, you win! We screwed it all up and it’s all going to go to hell in a handbasket, we’re stupid idiots and need you to hold us by the hands for the rest of our life. Is that what you want? [Your husband's name] to run to mommy first every time we have a decision to make, and clear it with you? If that’s not what you want, can’t you show a little support? ” and see what the interfering old sow says.

You and your husband are the ones purchasing a home and most likely comfortable enough and have made necessary steps to ensure that you are capable of making it work so don’t worry so much about what she thinks. If you feel you can do it go for it. If your Husband has doubts about it weigh in on your financial situation, make him see that he has nothing to worry about and that things will be fine and there’s no problem with the home you will be buying.

That house very well may be worth $80-90,000 next year so be prepared to owe more than it is worth. If you feel it is…then go for it.

If not, as other people are telling you…then wait for a better deal…or make a lower offer. I cannot imagine there are many other offers on that property, and I do not think you negotiated the best deal.

Offer them $75k and work up.

starting prices for something decent over here is about $300,000.00