My friends, my boyfriend and my parents don’t support me, yet I am quite confident this time I will be able to make it with my new startup. I just hope their lack of confidence doesn’t wear me out.

Don't seek out their approval. Keep it quite and get it done and THEN share it. You already know they're pessimists and it seems like you know the effect they have on you so try to midget that as much as possible. Isolate this initiative. Go meet some fellow entrepreneurs I think you'll find a more supportive community with them.

I wish you all the best. Thats great advice above. Most people wish us to fail or think we're foolish. This is mostly because they don't have the courage themselves..

I cannot count how many times my friends first response to anything entrepreneurial I have wanted to do is, "That'll never work". And my parents only ever wanted me to have a job for life.

Don't give up. Find you community (physical and online). Oh, you will have lots of "Should I keep going? Is it going to work? self-doubts and ups and downs, but anyone building or creating ANYTHING has that.

Keep swinging the bat. You will eventually hit one out of the park!

put up boundaries with them and tell them not to cross those boundaries

they'll probably cross the line again -- make sure you blast them for doing so and that'll be the end of it

So why are you talking to them about it?