I'm not going to tell you what to do. I am going to point out the red flags you cited and ask what you would say to a friend who was considering dating someone who behaves like this.

he kept talking about... that i should’ve ditched my bf for him

In other words, he did not respect your relationship when you were in one.

badmouthed not only his gf of a few years

He handles struggles in a relationship by badmouthing his partner to others,

he left her bc she showed signs of schizophrenia

and uses an armchair diagnosis as an excuse to get out of a relationship instead of just saying it's not working for him anymore like an adult.

he kept guilttripping me when i said i didn’t want to be his gf

He doesn't care about your preferences, and tries to manipulate you when they don't match his.

That man has more red flags than a flag football team.

Girl, I can't believe no one here is telling you that the behavior you've described is absolutely not "having a man that treats you right". Guilt tripping, trashing his own girlfriend while being with her, telling you to be unfaithful, ignoring your homosexuality...

Hell, the way you've described him makes me wonder if his girlfriend was actually schizophrenic or if he just gaslit the fuck out of her and ditched her when it started to catch up to him. Did you know her personally? Did she show signs of schizophrenia that couldn't be explained by gaslighting? Did he try to work with her through her potential schizophrenia? That'd be another huge red flag: if she showed signs of disability and instead of trying to work with her, he dumped her.

Don't do it.

You're just sad, hurt, and about to get yourself into a hell of a lot more hurt if you listen to this strange compulsion of yours. Chill. Take a deep breath. Find some lesbian chicks. There've gotta be dommy lesbians around you if you're in a somewhat populated area in the US. Make friends, fuck your friends, have fun, and maybe you'll eventually end up with a girlfriend or two (and maybe a trans puppygirl too).

As a straight guy , stat the fuck away from that guy

This situation seems messy. Breaking up and going straight to someone else before you work on yourself seems like a mistake. This friend also seems to not be trustworthy. Why did you block them in the first place?

ik he doesn't care about consent

That's it. That's all your post needed to include. Literally everything else is unnecessary. Your history with your ex is irrelevant to this critical factor.

This is the only piece of information that matters, and it screams, "Hell, no." This man shouldn't exist in your romantic space.

Fight the loneliness by working hard over a year to build platonic friendships with groups of people. And then you'll be able to reenter the arena of romance with a level head, unclouded. Don't let loneliness cave your standards down. That almost never leads to anything lasting and satisfactory. I'm sorry for the pain you're going through but the guy you say you're considering will only severely worsen things, based on your descriptions.

You blocked him for a reason

You need to sort yourself out. First of all you need to find out if you even want to be with guys, girls, or which ever fits your mood. Try exploring your sexuality and find out what you want. You will do yourself no good wasting time with boys making you unfulfilled that could have been better spent smashing gashes with lasses that make you happier.

Ex-friend sounds like he won't actually be a good boyfriend because of how much he shit talks others, tries to emotionally manipulate you, and doesn't know how to recognize and "see" you.

Learn to be happy by yourself or you will never know how to be happy with someone else.

Best advice I can give at 40 is simple: Don't worry or even think about dating anyone because of relationship reasons. Be the best version of you and make yourself happy first. If you are balanced and in a good place, you'll meet someone in similar straights and it will work out right.

Try volunteering in your community for a day. Just try it. Meeting people that are also volunteering is a good way to find great people that have the kinds of qualities that lead to life long friends. It will also put life in perspective.

Chasing relationships always lead me to bad places.

You said you probably don’t like guys. Your bio says you’re a lesbian. Could you perhaps try to find girls who act the way you’re looking for and forget the other people? That man is not healthy for you, and you could just be looking for anyone out of loneliness.

Good luck to you 🫂

My simple adive : do what you want to do and don't do what's you don't want to do.

Lots of details here that I could comment on - but most direct advice is don't do a rebound - give yourself time before you start any new relationships.