This is a very kind hearted way of seeing things, but it is very Lacey centric.
Lacey might not be purely selfish, sure, no one is pure anything, she obviously is a mix of things, but one of these things, actually the predominant one is that she is indded very selfish.
When Lacey leaves for 4 years she does it for herself, was she entitled to it? probably, was she right to lie without giving MC any closure? No.
Both of those actions are super selfish and to be frank, cowardly.
I can look with a kind eye since I do have quite a bit of experience with abused children, my own adopted sister is one and she absolutely hates confrontations even to her own detriment.
Ignoring MC was again very selfish and cruel, lets be honest the only person Lacey is actually cruel with is MC, if you want to look at the present just look at the Will situation, she misunderstands and then goes nuclear on MC hitting him on his weakest spot, a spot she repeatedly hits with her blunders, this time was hit with purpose.
I am actually more fond of Lacey than I am for MC, which is a super weak (and racist

) man or even some of the friends like Mia, that act as complete enablers, never putting their foot down for her own good.
Lying for weeks to your husband to go to parties, breaking rules and attacking MC for asking simple questions such as Barty's behaviour do show that Lacey is not as good as she portrays herself.
I think you misunderstand Anna approach to gardening

.
True to start planting seeds you need to clean up, but also the cleaning up has to be done carefully and slowly.
Why? Because you risk to actually kill allso the good plants or make the terrain inhospitable (is this the right word??).
We are told and we see that MC is fragile and needs a gentle touch, if she cared about him like she says, she would have taken that approach immediately.
She doesn't because she doesn't want to go through months or years of rebuilding, she wants results, immediately because her impulse control is comparable to a toddler's.
So is Lacey a monster plotting evil? no
Is she a saint? NOOOOO
I completely agree on all points, but you have to realize that she didn't leave him in hell, she created the hell.
She mentions how much she knew MC, while she didn't even know about the rules, which was MC WAY OF LIFE, so she actually didn't know him that well.
She forgot about MC as soon as she found another crutch, true, but I believe the initial intention was really to be in a better state for MC.
Was the whole thing selfish as hell? yes
Did it have the usual Lacey collateral damage? YES
She even made up a convenient story in her head on how MC was "living the life" to actually excuse herself from her awful deeds, she would regret that later, having broken the only person that actually really gave a shit about her.
She was having fun at parties and when they became not so fun due to the drug abuse + having tried everything possible she decided to come back, actually she wasn't planning to come back at all until Anna the fucking MVP actuallly managed to get in contact with her and save MC.
Who knows, if Anna didn't call she could have been with Isaac by now, since she was actuallly thinking about it and he doesn't seem to take no for an answer.
Yup anna makes some questionable choices, like erasing the recording of isaac, but she is a real one.
I'd like to pick both of your minds about Mia, I have a strong problem with her characterization, she understood that Lacey was a broken shell of a girl and yet she never stopped pushing Lacey to degrade herself more and more.
Her initial reason? Llacey needed to say fuck you to her abusive parents, the plan? Making her become the campus public toilet.
It was just abuse, Mia even encourages her about the Evan thing until she finds herself in the situation to be the only one left out.
But wasn't she raped and abused? So a rapey scenario is not GREAt and exciting? Having Lacey thinking about a potential rapist while fucking MC is to be considered hot?
I don't know what the author had in mind, but he really fucked up on this one.
You seem to be on different areas of the spectrum so, give me your thoughts.