How's it going this week? I am feeling like a SAHM failure on and off too. A lot of these mamas are right - it DOES get easier as your LO gets older. But then it sort of gets harder too... 
I remember all the issues you are mentioning the first 3 months - the impossibility of juggling their needs, the impossibility of going out, oversupply, the sleep deprivation, etc, etc etc. Over time, most of that got all figured out and DD is actually the most chill little baby ever. She is seriously so laid back and went from SCREAMING HER HEAD OFF for hours a day between 6-12 weeks to crying almost NEVER just shy of 7 months. But we are also totally alone here (no friends, no family, no.body.) .. we moved when DD was 3 months. And my DS (just turned 3) decided this is good time to go through regression (from full-time potty trained to full time diapers, night waking, climbing in my DD's crib, and flat out saying "I'm a baby. I wanna be a baby."). That's what has made this part harder for me... now that DD sits and crawls, DS has turned insanely jealous and no amount of kiss, cuddles, and one-on-one time is enough. So actually I would say parenting the OLDER child has gotten harder, the baby has become cake.
The one thing that saves us is going out. I started when DD was just over 3 months and now we go pretty much everyday. I typically wear her at the park so I can have my hands free for DS while he's climbing and what-not. I got over the whole NIP thing..... I realized if any of us were ever gonna have any sanity, I'd just have to suck it up. Besides, I figured I literally don't know anyone in 200 miles, how embarassing could it be...? 
I pack our bag the night before - wipes and diapers, snacks & underwear (diapers?! GRRR) for DS, water, sunscreen, extra clothes, and what have you. After the morning nap ends and everyone seems in a decent mood, I just go. Both kids moods are about a 100000% better when we're not in the 900 sq ft apt with no outside space.
I also had (several) huge talks with my DH. We've never had anything even remotely close to a "struggle" period before so I just laid it all out there - I'm drowning. Help me more. Do the laundry. Take DS to the park. I'm going running - here's the kids. When you get home from work, the day is not over. You worked all day, I worked all day, now we've got more work and parenting to do. I've never been so direct with my DH before but he says he just needs to know what I need.. so I tell him! If your DH is your only help, make sure he helps!
On the bright side, I've encouraged my kids to sleep at the same time (except obviously DD takes 3 day naps, and DS only takes one). We ALL (YES, me too!) nap together around 1 pm. I lay with DS and get him to sleep first, and then nurse-nap with DD. Pretty much the same at bedtime (which is 730 for DS & 8 for DD). We have to get up at 530 around here... but at least after 8 pm DH & I can have our time together. We usually do an hour of "stuff" cleaning, studying, or whatever, and then an hour just hanging together. This time together SERIOUSLY helps ease any tension caused by how hard parenting 2 kids is!
Hmm that's all I can think of for right now and I'm off to put DD down......... just wanting to let you know much of this I felt exactly and almost all of it is gone (though new problems arise...)! Gradual betterment kind of sucks but one day you will wake up and realize it's not QUITE as hard as it was before.
*Sigh*.. I'm still hoping to meet people too...
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