Hello Switzerland:
First, I'm so sorry that your dopey parents won't give you credit for being the smart cookie you are!!! Ofcourse, you seem to realize that their Nish behaviour is part of their problem....not a reflection of anything real.
The reality is.....you are an intelligent person who has worked hard to succeed and is succeeding, regardless of their lack of support/praise/
pride/encouragement! Good for you!! You are doing it...regardless of them and their problem/s.
Second.....I think you are doing the right thing by not bothering to mention your return to school (and Congratulations on being accepted!! Yay again for you!!! You must be doing a lot of things right, have what it takes, be showing the correct attributes.....for them to accept you and that....is a great accomplishment already!! So way to go!!!)
How did you feel after those few words of praise? We all need praise eh?
Third.....another good thing....your coming here for support. If your parents won't be encouraging you along the way to success, the people here certainly will! Good idea...seeking some positive feedback from others. Your parents can go play with their lego (

). The fact is..you are an adult, who is capable of finding the support you need, and succeeding in your goals, without your parents support. You've done it so far and will continue to do so.
And last......I think the best possible way to avoid self-sabbotage is to continue doing what you're doing....by going for what you want, without including them (thereby giving them the chance to belittle/insult/seize the rewards for your achievements, and also......
By self-affirmation. Spend time each day affirming your goals, your achievements, your good assets, your abilities. You have many!! Reward yourself mentally by pointing them out, frequently, and encourage yourself to go for it! I know this does not give the emotional warmth of a few kind words from a parent.....but the fact is...your parents are not going to give this to you, no matter what you achieve. I guess the bottom line is that you must do it for yourself....and reach out to others...for support...when you feel you need more encouragement.
I admire you for going back to school!! That is a big step. It will require much work and consentration and effort and time. It is not an easy thing to do (I don't know your age but if you aren't fresh out of school.....it's gotta be tougher to get back into the swing). I'm so glad to hear that you are doing this for yourself and to improve your life (possibly the lives of your family...if it will lead to an increase in income). You are a risk-taker...because it's risky to put out the money for school, make the committment, and chance failure (which can happen for any number of reasons). You're taking that risk anyway, and that tells me that you are thinking positively in that you believe you will succeed!! Keep thinking that way and you will!!!
Best of luck, Switzerland!!! I'm cheering you all the way!!!
GFN